Amplitude-modulated Noise Research Articles

Modulation Spectra Capture EEG Responses to Speech Signals and Drive Distinct Temporal Response Functions.

Speech signals have a unique shape of long-term modulation spectrum that is distinct from environmental noise, music, and non-speech vocalizations. Does the human auditory system adapt to the speech long-term modulation spectrum and efficiently extract critical information from speech signals? To answer this question, we tested whether neural responses to speech signals can be captured by specific modulation spectra of non-speech acoustic stimuli. We generated amplitude modulated (AM) noise with the speech modulation spectrum and 1/f modulation spectra of different exponents to imitate temporal dynamics of different natural sounds. We presented these AM stimuli and a 10-min piece of natural speech to 19 human participants undergoing electroencephalography (EEG) recording. We derived temporal response functions (TRFs) to the AM stimuli of different spectrum shapes and found distinct neural dynamics for each type of TRFs. We then used the TRFs of AM stimuli to predict neural responses to the speech signals, and found that (1) the TRFs of AM modulation spectra of exponents 1, 1.5, and 2 preferably captured EEG responses to speech signals in the δ band and (2) the θ neural band of speech neural responses can be captured by the AM stimuli of an exponent of 0.75. Our results suggest that the human auditory system shows specificity to the long-term modulation spectrum and is equipped with characteristic neural algorithms tailored to extract critical acoustic information from speech signals.

Effect of sinusoidally amplitude modulated broadband noise stimuli on stream segregation in individuals with sensorineural hearing loss

Background and Aim: Auditory stream segre­gation is a phenomenon that splits sounds into different streams. The temporal cues that contri­bute for stream segregation have been previ­ously studied in normal hearing people. In peo­ple with sensorineural hearing loss (SNHL), the cues for temporal envelope coding is not usually affected, while the temporal fine structure cues are affected. These two temporal cues depend on the amplitude modulation frequency. The present study aimed to evaluate the effect of sin­usoidal amplitude modulated (SAM) broadband noises on stream segregation in individuals with SNHL. Methods: Thirty normal hearing subjects and 30 subjects with mild to moderate bilateral SNHL participated in the study. Two experi­ments were performed; in the first experiment, the AB sequence of broadband SAM stimuli was presented, while in the second experiment, only B sequence was presented. A low (16 Hz) and a high (256 kHz) standard modulation fre­quency were used in these experiments. The subjects were asked to find the irregularities in the rhythmic sequence. Results: Both the study groups could identify the irregularities similarly in both the experi­ments. The minimum cumulative delay was sli­ghtly higher in the SNHL group. Conclusion: It is suggested that the temporal cues provided by the broadband SAM noises for low and high standard modulation frequencies were not used for stream segregation by either normal hearing subjects or those with SNHL. Keywords: Stream segregation; sinusoidal amplitude modulation; sensorineural hearing loss

The Temporal Fine Structure of Background Noise Determines the Benefit of Bimodal Hearing for Recognizing Speech

Cochlear implant (CI) users have more difficulty understanding speech in temporally modulated noise than in steady-state (SS) noise. This is thought to be caused by the limited low-frequency information that CIs provide, as well as by the envelope coding in CIs that discards the temporal fine structure (TFS). Contralateral amplification with a hearing aid, referred to as bimodal hearing, can potentially provide CI users with TFS cues to complement the envelope cues provided by the CI signal. In this study, we investigated whether the use of a CI alone provides access to only envelope cues and whether acoustic amplification can provide additional access to TFS cues. To this end, we evaluated speech recognition in bimodal listeners, using SS noise and two amplitude-modulated noise types, namely babble noise and amplitude-modulated steady-state (AMSS) noise. We hypothesized that speech recognition in noise depends on the envelope of the noise, but not on its TFS when listening with a CI. Secondly, we hypothesized that the amount of benefit gained by the addition of a contralateral hearing aid depends on both the envelope and TFS of the noise. The two amplitude-modulated noise types decreased speech recognition more effectively than SS noise. Against expectations, however, we found that babble noise decreased speech recognition more effectively than AMSS noise in the CI-only condition. Therefore, we rejected our hypothesis that TFS is not available to CI users. In line with expectations, we found that the bimodal benefit was highest in babble noise. However, there was no significant difference between the bimodal benefit obtained in SS and AMSS noise. Our results suggest that a CI alone can provide TFS cues and that bimodal benefits in noise depend on TFS, but not on the envelope of the noise.

Age-related changes in the temporal processing of acoustical signals in the auditory cortex of rats

Age-related hearing loss is manifested primarily by a decreased sensitivity to faint sounds, that is, by elevation of the hearing thresholds. Nevertheless, aging also affects the ability of the auditory system to process temporal parameters of the sound stimulus. To explore the precision and reliability of auditory temporal processing during aging, responses to several types of sound stimuli were recorded from neurons of the auditory cortex (AC) of young and aged anaesthetized Fischer 344 rats. In response to broad-band noise bursts, the aged rats exhibited larger response magnitudes, a higher proportion of monotonic units, and also a larger variability of response magnitudes, suggesting a lower stability of the rate code. Of primary interest were the responses to temporally structured stimuli (amplitude-modulated (AM) noise, frequency-modulated (FM) tones, and click trains) recorded separately in the right and left AC. Significant differences of temporal processing were already found between the neuronal responses in the left and right AC in the young animals: for the click trains, the left hemisphere exhibited a greater responsiveness to higher repetition rates, lower vector strength values, and a lower similarity of responses. The two hemispheres were also affected differently by aging. In the right hemisphere, neurons in the aged animals displayed worse synchronization with the AM noise and clicks, but better synchronization with the FM tone. In the left hemisphere, neuronal synchronization with the stimulus modulation improved at a higher age for all three stimuli. The results show that the ability of the aging auditory system to process temporal parameters of the stimulus strongly depends on the stimulus type and on laterality. Furthermore, the commonly reported age-related decline in the temporal processing ability cannot be regarded as general as, at least at the neuronal level in the AC, objective measures of the temporal representation often exhibit age-related improvement instead of deterioration.

EEG Connectivity Analysis Using Denoising Autoencoders for the Detection of Dyslexia.

The Temporal Sampling Framework (TSF) theorizes that the characteristic phonological difficulties of dyslexia are caused by an atypical oscillatory sampling at one or more temporal rates. The LEEDUCA study conducted a series of Electroencephalography (EEG) experiments on children listening to amplitude modulated (AM) noise with slow-rythmic prosodic (0.5-1[Formula: see text]Hz), syllabic (4-8[Formula: see text]Hz) or the phoneme (12-40[Formula: see text]Hz) rates, aimed at detecting differences in perception of oscillatory sampling that could be associated with dyslexia. The purpose of this work is to check whether these differences exist and how they are related to children's performance in different language and cognitive tasks commonly used to detect dyslexia. To this purpose, temporal and spectral inter-channel EEG connectivity was estimated, and a denoising autoencoder (DAE) was trained to learn a low-dimensional representation of the connectivity matrices. This representation was studied via correlation and classification analysis, which revealed ability in detecting dyslexic subjects with an accuracy higher than 0.8, and balanced accuracy around 0.7. Some features of the DAE representation were significantly correlated ([Formula: see text]) with children's performance in language and cognitive tasks of the phonological hypothesis category such as phonological awareness and rapid symbolic naming, as well as reading efficiency and reading comprehension. Finally, a deeper analysis of the adjacency matrix revealed a reduced bilateral connection between electrodes of the temporal lobe (roughly the primary auditory cortex) in DD subjects, as well as an increased connectivity of the F7 electrode, placed roughly on Broca's area. These results pave the way for a complementary assessment of dyslexia using more objective methodologies such as EEG.

Dynamics and Hierarchical Encoding of Non-compact Acoustic Categories in Auditory and Frontal Cortex.

Categorical perception is a fundamental cognitive function enabling animals to flexibly assign sounds into behaviorally relevant categories. This study investigates the nature of acoustic category representations, their emergence in an ascending series of ferret auditory and frontal cortical fields, and the dynamics of this representation during passive listening to task-relevant stimuli and during active retrieval from memory while engaging in learned categorization tasks. Ferrets were trained on two auditory Go-NoGo categorization tasks to discriminate two non-compact sound categories (composed of tones or amplitude-modulated noise). Neuronal responses became progressively more categorical in higher cortical fields, especially during task performance. The dynamics of the categorical responses exhibited a cascading top-down modulation pattern that began earliest in the frontal cortex and subsequently flowed downstream to the secondary auditory cortex, followed by the primary auditory cortex. In a subpopulation of neurons, categorical responses persisted even during the passive listening condition, demonstrating memory for task categories and their enhanced categorical boundaries.

Post-natal development of the envelope following response to amplitude modulated sounds in the bat Phyllostomus discolor

Bats use a large repertoire of calls for social communication, which are often characterized by temporal amplitude and frequency modulations. As bats are considered to be among the few mammalian species capable of vocal learning, the perception of temporal sound modulations should be crucial for juvenile bats to develop social communication abilities. However, the post-natal development of auditory processing of temporal modulations has not been investigated in bats, so far. Here we use the minimally invasive technique of recording auditory brainstem responses to measure the envelope following response (EFR) to sinusoidally amplitude modulated noise (range of modulation frequencies: 11–130 Hz) in three juveniles (p8-p72) of the bat, Phyllostomus discolor. In two out of three animals, we show that although amplitude modulation processing is basically developed at p8, EFRs maturated further over a period of about two weeks until p33. Maturation of the EFR generally took longer for higher modulation frequencies (87–130 Hz) than for lower modulation frequencies (11–58 Hz).

Spectro-Temporal Processing in a Two-Stream Computational Model of Auditory Cortex.

Neural processing of sounds in the dorsal and ventral streams of the (human) auditory cortex is optimized for analyzing fine-grained temporal and spectral information, respectively. Here we use a Wilson and Cowan firing-rate modeling framework to simulate spectro-temporal processing of sounds in these auditory streams and to investigate the link between neural population activity and behavioral results of psychoacoustic experiments. The proposed model consisted of two core (A1 and R, representing primary areas) and two belt (Slow and Fast, representing rostral and caudal processing respectively) areas, differing in terms of their spectral and temporal response properties. First, we simulated the responses to amplitude modulated (AM) noise and tones. In agreement with electrophysiological results, we observed an area-dependent transition from a temporal (synchronization) to a rate code when moving from low to high modulation rates. Simulated neural responses in a task of amplitude modulation detection suggested that thresholds derived from population responses in core areas closely resembled those of psychoacoustic experiments in human listeners. For tones, simulated modulation threshold functions were found to be dependent on the carrier frequency. Second, we simulated the responses to complex tones with missing fundamental stimuli and found that synchronization of responses in the Fast area accurately encoded pitch, with the strength of synchronization depending on number and order of harmonic components. Finally, using speech stimuli, we showed that the spectral and temporal structure of the speech was reflected in parallel by the modeled areas. The analyses highlighted that the Slow stream coded with high spectral precision the aspects of the speech signal characterized by slow temporal changes (e.g., prosody), while the Fast stream encoded primarily the faster changes (e.g., phonemes, consonants, temporal pitch). Interestingly, the pitch of a speaker was encoded both spatially (i.e., tonotopically) in Slow area and temporally in Fast area. Overall, performed simulations showed that the model is valuable for generating hypotheses on how the different cortical areas/streams may contribute toward behaviorally relevant aspects of auditory processing. The model can be used in combination with physiological models of neurovascular coupling to generate predictions for human functional MRI experiments.

Amplitude Modulated Noise for Tinnitus Suppression in Tonal and Noise-Like Tinnitus

Background: The phenomenon of short-term tinnitus suppression by different forms of acoustic stimulation is referred to as residual inhibition (RI). RI can be triggered in the majority of tinnitus cases and was found to be depending on the used intensity, length or types of sounds. Past research already stressed the impact of noise stimulation as well as the superiority of amplitude modulated (AM) pure tones at the individual tinnitus frequency for RI in tonal tinnitus. Recently a novel approach for the determination of noise-like tinnitus characteristics was proposed. Objectives: The aim of the present study was to investigate whether in participants with noise-like tinnitus RI can be increased by AM noise stimuli according to the individual tinnitus frequency range. Methods: For this purpose the individual tinnitus characteristics (noise-like and tonal tinnitus) of 29 people affected by tinnitus (mean age = 55.59, 7 females, mean tinnitus duration = 159.97 months) were assessed via customizable noise-band matching. The objective was to generate bandpass filtered stimuli according to the individual tinnitus sound (individualized bandpass filtered [IBP] sounds). Subsequently, various stimuli differing in bandpass filtering and AM were tested with respect to their potential to induce RI. Participants were acoustically stimulated with 7 different types of stimuli for 3 min each and had to rate the loudness of their tinnitus after each stimuli. Results: Results indicate a general efficacy of noise stimuli for the temporary suppression of tinnitus, but no significant differences between AM and unmodulated IBP. Significantly better effects were observed for the subgroup with noise-like tinnitus (n = 14), especially directly after stimulation offset. Conclusions: The study at hand provides further insights in potential mechanisms behind RI for different types of tinnitus. Beyond that, derived principles may qualify for new or extend current tinnitus sound therapies.

Dynamics and Hierarchical Encoding of Non-Compact Acoustic Categories in Auditory and Frontal Cortex

Categorical perception is a fundamental cognitive function enabling animals to flexibly assign sounds into behaviorally relevant categories. This study investigates the nature of acoustic category representations, their emergence in an ascending series of ferret auditory and frontal cortical fields, and the dynamics of this representation during passive listening to task-relevant stimuli and also during active retrieval from memory during task performance. Ferrets were trained on two auditory Go-NoGo categorization tasks to discriminate two non-compact sets of sounds (tones or amplitude-modulated noise). Neuronal responses became progressively more categorical in higher cortical fields, especially during task performance. The dynamics of the categorical responses exhibited a cascading top-down modulation pattern that began earliest in frontal cortex, and subsequently flowed downstream to secondary auditory cortex, followed by primary auditory cortex. In a sub-population of neurons, categorical responses persisted even during the passive listening condition, demonstrating memory for task categories and their enhanced categorical boundaries.

Cortical Tracking of Complex Sound Envelopes: Modeling the Changes in Response with Intensity.

Characterizing how the brain responds to stimuli has been a goal of sensory neuroscience for decades. One key approach has been to fit linear models to describe the relationship between sensory inputs and neural responses. This has included models aimed at predicting spike trains, local field potentials, BOLD responses, and EEG/MEG. In the case of EEG/MEG, one explicit use of this linear modeling approach has been the fitting of so-called temporal response functions (TRFs). TRFs have been used to study how auditory cortex tracks the amplitude envelope of acoustic stimuli, including continuous speech. However, such linear models typically assume that variations in the amplitude of the stimulus feature (i.e., the envelope) produce variations in the magnitude but not the latency or morphology of the resulting neural response. Here, we show that by amplitude binning the stimulus envelope, and then using it to fit a multivariate TRF, we can better account for these amplitude-dependent changes, and that this leads to a significant improvement in model performance for both amplitude-modulated noise and continuous speech in humans. We also show that this performance can be further improved through the inclusion of an additional envelope representation that emphasizes onsets and positive changes in the stimulus, consistent with the idea that while some neurons track the entire envelope, others respond preferentially to onsets in the stimulus. We contend that these results have practical implications for researchers interested in modeling brain responses to amplitude modulated sounds.

The fluctuating masker benefit for normal-hearing and hearing-impaired listeners with equal audibility at a fixed signal-to-noise ratio.

Normal-hearing (NH) listeners can extract and integrate speech fragments from momentary dips in the level of a fluctuating masker, yielding a fluctuating-masker benefit (FMB) for speech understanding relative to a stationary-noise masker. Hearing-impaired (HI) listeners generally show less FMB, suggesting a dip-listening deficit attributable to suprathreshold spectral or temporal distortion. However, reduced FMB might instead result from different test signal-to-noise ratios (SNRs), reduced absolute audibility of otherwise unmasked speech segments, or age differences. This study examined the FMB for nine age-matched NH-HI listener pairs, while simultaneously equalizing audibility, SNR, and percentage-correct performance in stationary noise. Nonsense syllables were masked by stationary noise, 4- or 32-Hz sinusoidally amplitude-modulated noise (SAMN), or an opposite-gender interfering talker. Stationary-noise performance was equalized by adjusting the response-set size. Audibility was equalized by removing stimulus components falling below the HI absolute threshold. HI listeners showed a clear 4.5-dB reduction in FMB for 32-Hz SAMN, a similar FMB to NH listeners for 4-Hz SAMN, and a non-significant trend toward a 2-dB reduction in FMB for an interfering talker. These results suggest that HI listeners do not exhibit a general dip-listening deficit for all fluctuating maskers, but rather a specific temporal-resolution deficit affecting performance for high-rate modulated maskers.

Efficiency in glimpsing vowel sequences in fluctuating makers: Effects of temporal fine structure and temporal regularity.

Listeners' efficiency in glimpsing the target speech in amplitude-modulated maskers may depend on whether the target is perceptually segregated from the masker and on the temporal predictability of the target. Using synthesized vowel sequences as the target, recognition of vowel sequences in simultaneous amplitude-modulated noise maskers was measured as the signal-to-noise ratio (SNR) and the masker modulation rate were systematically varied. In Experiment I (Exp. I), the temporal fine structure of the target was degraded by synthesizing the vowels using iterated rippled noise as the glottal source. In Experiment II (Exp. II), the vowel sequences were constructed so that they were not isochronous, but instead contained randomized intervals between adjacent vowels. Results were compared to the predictions from a dip-listening model based on short-term SNR. The results show no significant facilitative effect of temporal fine structure cues on vowel recognition (Exp. I). The model predictions significantly overestimated vowel-recognition performance in amplitude-modulated maskers when the temporal regularity of the target was degraded (Exp. II), suggesting the influence of temporal regularity on glimpsing efficiency. Furthermore, the overestimations by the model were greater at lower SNRs and selective to moderate masker modulation rates (between 2 and 6 Hz).

Exploring the relationship between sound localization and individual use of spectral and temporal cues among hearing-impaired listeners

When locating a sound source, listeners are expected to rely more on spectral cues for elevation and temporal cues for azimuth. This work investigates whether sound localization ability can be predicted by individually-measured use of spectral and temporal cues. Participants were older adults with sensorineural hearing loss. Sound sources for the localization task were created in a virtual room, using a mix of virtual and physical loudspeakers in the front hemifield of the listener. Sources were distributed evenly between ±90 deg azimuth and ±20 deg elevation. The signal was a 1 s broadband 4-Hz amplitude-modulated noise. To assess the relationship between localization ability and use of spectral and temporal cues, listeners performed cue weighting and cue discrimination tasks. In the cue weighting task, listeners identified synthetic speech sounds that varied spectro-temporally. The cue discrimination task measured the smallest detectable difference in either spectral or temporal information among the same set of ambiguous speech sounds. Together, these tasks form a cue profile which identifies whether the listener relies to a greater extent on temporal or spectral cues. Older hearing-impaired listeners varied in their ability to localize sounds. Localization results will be discussed in the context of cue profiles and audiometry. [Work supported by NIH.]

Neural coding of the sound envelope is changed in the inferior colliculus immediately following acoustic trauma.

Sensorineural hearing loss is often accompanied by difficulties with understanding speech in fluctuating backgrounds, suggesting that neural coding of complex sound features, such as the sound envelope, is impaired. Here, we studied how temporal and rate coding of the envelope is affected in the inferior colliculus immediately after acoustic trauma. Neural activity in response to amplitude-modulated noise was recorded from the inferior colliculus of the guinea pig, before and immediately after a 1-hr 11-kHz acoustic trauma. Units with a characteristic frequency (CF) below the trauma frequency (<11kHz) showed increased response gains, a measure for temporal coding of the sound envelope, especially at low modulation frequencies (≤128Hz). Units with a CF>11kHz, which had large acoustic trauma-induced threshold shifts, had decreased response gains to amplitude-modulated noise. Shapes of temporal modulation transfer functions shifted toward a higher proportion of low-pass shapes in low-CF units, and to less band-pass shapes in high-CF units. Furthermore, driven firing rates decreased, especially at high modulation frequencies for high-CF units. The observed changes occurred immediately following trauma and were thus a result of the immediate trauma-induced damage to the auditory system. If also present in human subjects, reduced response gains in high-frequency units could disrupt coding of consonants and consequently impair speech understanding in noisy environments. Moreover, the enhanced temporal coding by low-CF units of the low modulation frequencies could overly amplify responses to low-frequency noise, further deteriorating listening in noise.

Compressive Sensing for Detecting Ships With Second-Order Cyclostationary Signatures

Amplitude modulation of the broadband propeller noise as a result of the cavitation yields a second-order cyclostationary ship-radiated noise. The spectrum of the modulating signal, consisting of the so-called propeller (or cavitation) tonals, enables the detection and the classification of the submarines or surface ships. However, data acquisition for this purpose causes vast data sizes due to high sampling rates and multiple sensor deployment. To mitigate the negative effects of this acquisition process such as on energy efficiency, hardware complexity, and storage capacity, we propose a scheme for compressive sensing of propeller tonals. We show that the spectral correlation function of cyclostationary propeller noise is sparse and derive a linear relationship between the compressive and Nyquist-rate cyclic modulation spectra, i.e., the approximation of spectral correlation function that allows utilizing matrix representations required in compressive sensing. It also enables use of the cyclic modulation coherence, i.e., the normalized cyclic modulation spectrum, to demonstrate the effect of compressive sensing in terms of statistical detection. We compare the recovery and detection performance results of the sparse approximation algorithms based on the so-called iterative hard thresholding and compressive sampling matching pursuit. Results show that compression is achievable without affecting the detection performance negatively. The main challenges are the weak modulation, low signal-to-noise ratio, and nonstationarity of the ambient noise, all of which reduce the sparsity level, hence causing degraded recovery and detection performance.

Acute motor and vocal response of humpback whales (Megaptera novaeangliae) to playback of amplitude-modulated noise: A method to test frequency range of hearing

The frequency hearing range of mysticete cetaceans remains elusive despite a growing concern about the negative impacts of anthropogenic noise. A playback study was conducted in the Maui Nui region of Hawaii during March 2018. Stationary humpback whales (i.e., single singers or silent dyads) were targeted due to their predictable behavior that allowed for observations pre, during, and post-playback. Playback consisted of amplitude-modulated noise that was broadband, high-pass filtered, or 1/3 octave bandpass filtered. The animal’s motor behavior was recorded by video from a swimmer positioned above the animal. Acoustic playback and acquisition was performed from a small vessel approximately 41 m to 56 m from a targeted animal. A total of 16 playbacks were conducted with estimated received levels between 116 dB–138 dB RMS (re 1 μPa). Motor responses ranged from abruptly swimming away to subtle fluke movements with a median response latency of 1.7 sec (n = 7). Vocal responses ranged from abrupt song termination to unexpected changes in song unit pattern, with a median response latency of 2.94 sec (n = 8). This novel playback methodology was effective at producing and measuring motor and vocal responses to sound and may be useful in measuring the hearing range of mysticetes.

Human medial efferent activity elicited by dynamic versus static contralateral noises

The medial olivocochlear reflex (MOCR) modifies cochlear amplifier function to improve encoding of signals in static noise, but conflicting results have been reported regarding how the MOCR responds to dynamic, temporally-complex noises. The current study utilized three MOCR elicitors with identical spectral content but different temporal properties: broadband noise, amplitude-modulated noise, and speech envelope-modulated noise. MOCR activity was assessed using contralateral inhibition of transient-evoked otoacoustic emissions in 27 normal-hearing young adults. Elicitors were presented contralaterally at two intensities of 50 and 60 dB SPL. Magnitude and growth of contralateral inhibition with increasing elicitor intensity were compared across the three elicitor types. Results revealed that contralateral inhibition was significantly larger at the elicitor intensity of 60 dB SPL than at 50 dB SPL, but there were no significant differences in the magnitude and growth of inhibition across the three elicitors, contrary to hypothesis. These results suggest that the MOCR responds similarly to both static and dynamic noise.

Masking of synthesized vowel sequences: The potential roles of perceptual segregation

Modulation masking is known to impact speech intelligibility, but it is not clear how this phenomenon interacts with the perceptual segregation between the target speech and background noise. Using an experimental task in which listeners identified synthesized-vowel sequences in amplitude-modulated noises, a previous study from our laboratory found few signs of modulation masking, contrary to the findings of speech-on-speech masking experiments. It is hypothesized that modulation masking at a low rate (<6 Hz) may reflect failures of segregating the target speech from the noise. The current study systematically removed segregation cues and evaluated the amount of modulation masking. These segregation cues included the periodicity in the temporal fine structure of the target vowel sequences (in Exp. I) and the temporal regularity of the vowel sequences (in Exp. II). Results will be discussed in terms of the potential interactions between modulation masking and perceptual segregation.

Whispered Mandarin has no production-enhanced cues for tone and intonation

It is often assumed, explicitly or implicitly, that speakers generate special cues in whispered tone and intonation to make up for the absence of fundamental frequency. The present study examined this assumption with one production and three perception experiments. The production experiment compared duration, intensity, formants and spectral tilt of phonated and whispered Mandarin monosyllabic utterances with four lexical tones spoken as either statements or questions. For tones, no acoustic properties were found to occur only in whispered but not in phonated utterances. For intonation, some spectral tilt measurements differed between the two phonation types. The two tone perception experiments used phonated and whispered utterances as well as amplitude-modulated noise based on those utterances as stimuli. Results show that once turned into amplitude-modulated noise, phonated and whispered tones had similar identification patterns, indicating that the non-F0 tonal cues in whispers were already in phonated speech. The intonation perception experiment used original utterances as stimuli and showed a substantial drop in overall identification rate and an overwhelming bias towards statement. Thus the spectral tilt differences found in the acoustic analysis were not helpful for intonation perception. Possible reasons for the lack of effective enhancement in whispered speech were discussed.