Low-frequency Tones Research Articles

Outer hair cells stir cochlear fluids.

We hypothesized that active outer hair cells drive cochlear fluid circulation. The hypothesis was tested by delivering the neurotoxin, kainic acid, to the intact round window of young gerbil cochleae while monitoring auditory responses in the cochlear nucleus. Sounds presented at a modest level significantly expedited kainic acid delivery. When outer-hair-cell motility was suppressed by salicylate, the facilitation effect was compromised. A low-frequency tone was more effective than broadband noise, especially for drug delivery to apical locations. Computational model simulations provided the physical basis for our observation, which incorporated solute diffusion, fluid advection, fluid-structure interaction, and outer-hair-cell motility. Active outer hair cells deformed the organ of Corti like a peristaltic tube to generate apically streaming flows along the tunnel of Corti and basally streaming flows along the scala tympani. Our measurements and simulations coherently suggest that active outer hair cells in the tail region of cochlear traveling waves drive cochlear fluid circulation.

Acoustic flow resonances in installed rectangular jets

Zonal Large Eddy Simulations (LES) of complex installed rectangular jet flows are performed for subsonic jet conditions of the Central Institute for Aviation Motors (CIAM) experiment, where a strong tone was reported. For far-field noise modelling, the zonal LES solutions are coupled with the permeable formulation of the Ffowcs Williams and Hawkings (FW-H) method. The obtained noise spectra predictions are compared with the acoustic measurements in the CIAM facility. To reduce statistical noise of the relatively short LES time series, contributions due to several dominant low frequency tones and the remaining broadband signal are computed separately, using a tailored Fourier transform technique for each signal type. For cross-validation, noise spectra measurements of an equivalent isolated round jet in the CIAM facility are compared with the empirical sJet model calibrated on the NASA Small Hot Jet Acoustic Rig (SHJAR) jet noise database. While the two datasets agree reasonably well for mid to high frequencies, larger discrepancies are observed for low frequencies, which are attributed to acoustic reflections in the non-anechoic CIAM facility. The differences in noise levels between the CIAM dataset and the sJet model representing the NASA jet noise data are used to determine the experimental uncertainty of the CIAM noise measurements for each frequency and observer angle. For the installed rectangular jet, it is shown that far-field noise spectra predictions of the zonal LES-FW-H method for both the fundamental tone, its sixth harmonic corresponding to the jet Strouhal number of around 1, and the broadband component are broadly within the experimental error bar for most observer angles. Some discrepancies between predictions of the zonal LES method and the CIAM measurements for the main low frequency tone for the 30° and 90°, where the experimental uncertainty at low frequencies is largest are also noted. After validating the acoustic solutions, spectral and conditional averaging analysis methods are applied to elucidate mechanisms of the acoustic-flow resonance in the installed rectangular jet flow. The numerical dispersion relation is obtained to analyse phase velocities of the upstream and downstream travelling pressure waves in the stream-wise direction. The conditional analysis of pressure fluctuations inside the jet reveals the emergence of internal reflection points corresponding to a rapid change of the acoustic wave phase as well as the saddle points interpreted as localised zones of vorticity shed from the side-wall edges. To independently investigate the effect of trailing edges and corner points of the jet embodiment geometry on closing the acoustic-flow resonance cycle, several modifications of the baseline rectangular nozzle are considered, such as introducing chevron-like lobes and cuts on the trailing edges of the side walls as well as smoothing the sharp corner points of the wall edges. Following the series of additional zonal LES runs with the modified installed nozzle geometries, an optimized tone-less modification of the original installed nozzle was obtained, in broad agreement with the conditional analysis results. The obtained tone-less modification of the installed rectangular jet is further analyzed to provide insights into its similarity and differences from the aeroacoustics of the reference isolated round jet in the same CIAM facility.

AI model for predicting adult cochlear implant candidacy using routine behavioral audiometry

ObjectiveTo describe an AI model to facilitate adult cochlear implant candidacy prediction based on basic demographical data and standard behavioral audiometry. MethodsA machine-learning approach using retrospective demographic and audiometric data to predict candidacy CNC word scores and AzBio sentence in quiet scores was performed at a tertiary academic center. Data for the model were derived from adults completing cochlear implant candidacy testing between January 2011 and March 2023. Comparison of the prediction model to other published prediction tools and benchmarks was performed. ResultsThe final dataset included 770 adults, encompassing 1045 AzBio entries, and 1373 CNC entries. Isophoneme scores and word recognition scores exhibited strongest importance to both the CNC and AzBio prediction models, followed by standard pure tone average and low-frequency pure tone average. The mean absolute difference between the predicted and actual score was 15 percentage points for AzBio sentences in quiet and 13 percentage points for CNC word scores, approximating anticipated test-retest constraints inherent to the variables incorporated into the model. Our final combined model achieved an accuracy of 87 % (sensitivity: 90 %; precision: 80 %). ConclusionWe present an adaptive AI model that predicts adult cochlear implant candidacy based on routine behavioral audiometric and basic demographical data. Implementation efforts include a public-facing online prediction tool and accompanying smartphone program, an embedded notification flag in the electronic medical record to alert providers of potential candidates, and a program to retrospectively engage past patients who may be eligible for cochlear implantation based on audiogram results.

Simple DFS and AOA simultaneous measurement scheme without directional ambiguity with co-frequency self-interference signal cancellation

A photonic method based on a dual-polarization dual-parallel Mach–Zehnder modulator (DPol-DPMZM) for the simultaneous measurement of the Doppler frequency shift (DFS) and angle of arrival (AOA) of microwave signals is proposed and demonstrated by simulation. The upper arm of each sub-DPMZM is driven by the echo and self-interference signals from the antenna, while the lower arm is driven by the reference signal 1 and reference signal 2. The phase and amplitude of the reference signal 1 are adjusted to match the interference signals for achieving the self-interference cancellation (SIC). At the central office (CO), the DFS and AOA can be acquired in real time without directional ambiguity by processing the two downconverted low-frequency tones in the photocurrent. The simulation results show that the presence of the SI signal will seriously interfere with the observation of the SOI frequency and waveform, and the self-interference cancellation depth of about 42 dB can be obtained after the SIC. The measurement errors of the DFS without direction ambiguity are within 0.2 Hz. After the Hilbert transformation of the intermediate frequency (IF) signal, the AOA can be measured from −87.31∘ to +87.31∘ with errors less than 3.9°. The system has a large bandwidth, excellent real-time performance, and better invisibility, and is expected to be used in modern electronic warfare systems.

Improved tactile speech perception using audio-to-tactile sensory substitution with formant frequency focusing

Haptic hearing aids, which provide speech information through tactile stimulation, could substantially improve outcomes for both cochlear implant users and for those unable to access cochlear implants. Recent advances in wide-band haptic actuator technology have made new audio-to-tactile conversion strategies viable for wearable devices. One such strategy filters the audio into eight frequency bands, which are evenly distributed across the speech frequency range. The amplitude envelopes from the eight bands modulate the amplitudes of eight low-frequency tones, which are delivered through vibration to a single site on the wrist. This tactile vocoder strategy effectively transfers some phonemic information, but vowels and obstruent consonants are poorly portrayed. In 20 participants with normal touch perception, we tested (1) whether focusing the audio filters of the tactile vocoder more densely around the first and second formant frequencies improved tactile vowel discrimination, and (2) whether focusing filters at mid-to-high frequencies improved obstruent consonant discrimination. The obstruent-focused approach was found to be ineffective. However, the formant-focused approach improved vowel discrimination by 8%, without changing overall consonant discrimination. The formant-focused tactile vocoder strategy, which can readily be implemented in real time on a compact device, could substantially improve speech perception for haptic hearing aid users.

Experiments on the peculiar region and threshold of oppressive or vibratory sensation caused by low-frequency pure tones

Experiments on the peculiar region and threshold of oppressive or vibratory sensation caused by low-frequency pure tones

Perceptual dimensions of fan sounds with different tonal characteristics

Fan noise is a common tonal noise source in people's everyday life. While tonal sounds at high frequencies often contribute to annoyance, the perception and evaluation of low-frequency tones is not fully understood. In the present study, the perceptual dimensions of 24 tonal prototype fan sounds were explored using a semantic differential consisting of 21 adjective scales that were rated by 40 participants. The synthesized sounds had the same sound pressure level of 55 dB(A) but differed in fundamental frequency and spectral envelope of the embedded tonal signatures Using a factor analysis, four perceptual dimensions were found that explain 59 % of the variance. Fan sounds with a fundamental frequency of 60 Hz were rated to be more "humming" (1st dimension) and more "pleasant" (2nd dimension) but less "buzzing" and less "beeping" (3rd dimension) in comparison to sounds with higher fundamental frequencies of 180 Hz and 300 Hz. An analysis of the relationships between the adjective scales and psychoacoustic metrics show that the "humming" ratings were highly correlated to a metric describing the relative contribution of low frequencies to the overall loudness. In contrast, psychoacoustic sharpness and tonality had smaller correlation coefficients with the "humming" ratings.

The influence of multisensory indoor environment on the perception of orange juice

Drinking (as well as eating) represents a fundamental multisensory experience of our lives. Recent studies have proposed the implementation of multisensory contexts to improve the taste perception of food and beverages. This topic becomes relevant when considering the possibility of promoting the consumption of healthy beverages (e.g., orange juice). Only a few studies have concentrated on the multisensory features of the indoor environment (e.g., acoustic and visual context) reporting effects on the perception of healthy beverages. This study investigates how multisensory indoor environments modify the taste perception while drinking orange juice. By controlling the room microclimate and combining the correlated colour temperature of lighting (i.e. warm and cool) and the background wall colour (i.e., red, green) in the Sens i-Lab, with different audio stimuli (i.e. low and high-frequency pure tone), participants were invited to taste the low-sugar orange juice and to rate the fruit juice aroma, sweetness, sourness, bitterness, freshness, and thickness. The results showed that listening to a high-frequency tone in an environment with warm lighting and a red background increases the sweetness perception of orange juice compared to the control environment. In addition, compared to the control condition, the juice aroma was rated more intense in almost all multisensory conditions and thicker with cool lighting and a green background while listening to a low-frequency tone. Our findings suggested that the development of multisensory design can contribute to interior design strategies and design innovation in food architecture, where people can improve their taste in healthy foods and beverages.

The effect of motion frequency and sound source frequency on steady-state auditory motion evoked potential

The ability of humans to perceive motion sound sources is important for accurate response to the living environment. Periodic motion sound sources can elicit steady-state motion auditory evoked potential (SSMAEP). The purpose of this study was to investigate the effects of different motion frequencies and different frequencies of sound source on SSMAEP. The stimulation paradigms for simulating periodic motion of sound sources were designed utilizing head-related transfer function (HRTF) techniques in this study. The motion frequencies of the paradigm are set respectively to 1-10 Hz, 15 Hz, 20 Hz, 30 Hz, 40 Hz, 60 Hz, and 80 Hz. In addition, the frequencies of sound source of the paradigms were set to 500 Hz, 1000 Hz, 2000 Hz, 3000 Hz, and 4000 Hz at motion frequencies of 6 Hz and 40 Hz. Fourteen subjects with normal hearing were recruited for the study. SSMAEP was elicited by 500 Hz pure tone at motion frequencies of 1-10 Hz, 15 Hz, 20 Hz, 30 Hz, 40 Hz, 60 Hz, and 80 Hz. SSMAEP was strongest at motion frequencies of 6 Hz. Moreover, at 6 Hz motion frequency, the SSMAEP amplitude was largest at the tone frequency of 500 Hz and smallest at 4000 Hz. Whilst SSMAEP elicited by 4000 Hz pure tone was significantly the strongest at motion frequency of 40 Hz. SSMAEP can be elicited by periodic motion sound sources at motion frequencies up to 80 Hz. SSMAEP also has a strong response at lower frequency. Low-frequency pure tones are beneficial to enhance SSMAEP at low-frequency sound source motion, whilst high-frequency pure tones help to enhance SSMAEP at high-frequency sound source motion. The study provides new insight into the brain's perception of rhythmic auditory motion.

Activation of Beta-adrenergic Receptors Upregulates the Signal-to-Noise Ratio of Auditory Input in the Medial Prefrontal Cortex and Mediates Auditory Fear Conditioning.

Norepinephrine (NE) is involved in auditory fear conditioning (AFC) in posttraumatic stress disorder (PTSD). However, it is still unclear how it acts on neurons. We aimed to investigate whether the activation of the β-adrenergic receptor (β-AR) improves AFC by sensitization of the prelimbic (PL) cortex at the animal, cellular, and molecular levels. In vivo single-cell electrophysiological recording was used to characterize the changes in neurons in the PL cortex after AFC. Then, PL neurons were locally administrated by the β-AR agonist isoproterenol (ISO), the GABAaR agonist muscimol, or intervened by optogenetic method, respectively. Western blotting and immunohistochemistry were finally used to assess molecular changes. Noise and low-frequency tones induced similar AFC. The expression of β-ARs in PL cortex neurons was upregulated after fear conditioning. Microinjection of muscimol into the PL cortex blocked the conformation of AFC, whereas ISO injection facilitated AFC. Moreover, PL neurons can be distinguished into two types, with type I but not type II neurons responding to conditioned sound and being regulated by β-ARs. Our results showed that β-ARs in the PL cortex regulate conditional fear learning by activating type I PL neurons.

Electrophysiological and behavioral assessment of binaural processing: Effects of age

Spatial hearing deteriorates with age, but the basis(es) of this age-dependency is not clear and could reflect both bottom-up and top-down factors. Since binaural processing depends in part on interaural time difference cues, this study assessed binaural temporal acuity using both objective and behavioral measures. Three tasks incorporating interaural time/phase differences were tested: (1) in-phase and out-of-phase frequency modulation (FM) detection as a function of FM rate; (2) upper frequency limit of in-phase versus out-of-phase tone discrimination; and (3) minimum audible angle for low frequency tones. Each task incorporated parallel behavioral and electrophysiological measures: For behavior, forced-choice adaptive methods were employed; for electrophysiology, the acoustic change complex (ACC) was recorded. Additional measures of peripheral auditory function, as well as cognitive status, were also collected. Young and middle-aged adults (n = 20 per age group) with normal audiometric hearing were tested. Differences in behavioral measures of binaural performance were noted between the two age groups and these were reflected to some extent in the ACC results. However, group differences were also noted in terms of cochlear function and in terms of cognitive abilities. This pattern of results suggests that age-related deterioration in spatial perception is likely to be multi-faceted.

Enhancement of phase-locking in rodents. II. An axonal recording study in chinchilla.

The trapezoid body (TB) contains axons of neurons residing in the anteroventral cochlear nucleus (AVCN) which provide excitatory and inhibitory inputs to the main monaural and binaural nuclei in the superior olivary complex (SOC). To understand the monaural and binaural response properties of neurons in the medial and lateral superior olive (MSO and LSO), it is important to characterize the temporal firing properties of these inputs. Because of its exceptional low-frequency hearing, the chinchilla (Chinchilla lanigera) is one of the widely used small animal models for studies of hearing. However, the characterization of the output of its ventral cochlear nucleus to the nuclei of the SOC is fragmentary. We obtained responses of TB axons to stimuli typically used in binaural studies and compared these responses to those of auditory nerve (AN) fibers, with a focus on temporal coding. We found enhancement of phase-locking and entrainment, i.e. the ability of a neuron to fire action potentials at a certain stimulus phase for nearly every stimulus period, in TB axons relative to AN fibers. Enhancement in phase-locking and entrainment are quantitatively more modest than in the cat but greater than in the gerbil. As in these species, these phenomena occur not only in low-frequency neurons stimulated at their characteristic frequency, but also in neurons tuned to higher frequencies when stimulated with low-frequency tones, to which complex phase-locking behavior with multiple modes of firing per stimulus cycle is frequently observed.

Experimental Demonstration of Multiband Comb-Enabled mm-Wave Transmission

A novel system architecture to realize multiple synchronized sources for multiband millimeter-wave (mm-Wave) transmission has been designed and experimentally demonstrated in two of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$W$</tex-math> </inline-formula> -band subbands at 100 and 112.5 GHz. The technique converts a distributed electro-optic comb, generated off-site, to a local electrical comb. The higher frequency tones in the resulting comb are extracted and used as mm-Wave oscillator sources. Thus, the architecture provides a method to generate multiple frequency-synchronized sources, using only a single electronic oscillator, with exceptionally low phase noise for simultaneous multiband mm-Wave transmission. Additionally, a lower frequency tone at 6.25 GHz is broadcasted over the air, providing synchronization reference between the mm-Wave transmitters and receivers.

Modeling the perceptions of Rumbling, humming and booming in the context of vehicle interior sounds

Sensations associated with an auditory perception of low-frequency tonal components are humming, rumbling and booming. While humming is commonly associated with an audible low-frequency tone, rumbling requires a temporal level fluctuation of such a tonal component and booming is associated with sounds that, in addition to the low-frequency tone, contain higher tonal components, which are related to the low-frequency tone. This study presents a model that predicts the magnitude of these sensations for interior sounds of vehicles with combustion engines running at low rotation rates, where low-frequency components are often audible. For the model development, own experimental data of recorded interior sounds and altered versions of these sounds were used. The model combines an auditory processing model with a Gaussian Process Regression approach. Key features of the auditory processing model are that it simulates the frequency-place transformation at the auditory periphery with a bank of auditory band pass filters and the frequency selectivity to temporal amplitude modulations with a bank of modulation band pass filters. It is shown that auditory filters up to a center frequency of 1000 Hz and modulation filters of up to 28 Hz are required for a good prediction of the data.

Hearing in African pygmy hedgehogs (Atelerix albiventris): audiogram, sound localization, and ear anatomy.

The behavioral audiogram and sound localization performance, together with the middle and inner ear anatomy, were examined in African pygmy hedgehogs Atelerix albiventris. Their auditory sensitivity at 60dB SPL extended from 2 to 46kHz, revealing a relatively narrow hearing range of 4.6 octaves, with a best sensitivity of 21dB at 8kHz. Their noise-localization acuity around the midline (minimum audible angle) was 14°, matching the mean of terrestrial mammals. The African pygmy hedgehog was not able to localize low-frequency pure tones or a 3-kHz amplitude-modulated tone when forced to rely on the interaural phase-difference cue, a trait shared by at least nine other mammals. The middle ear of Atelerix has a configuration including an ectotympanic which is not fused to the surrounding bones, a substantial pars flaccida, a synostosed malleo-ectotympanic articulation and a 'microtype' malleus. The hearing and sound localization of A. albiventris is compared to that of a broad range of other mammals. It is shown that a malleus morphology like that of Atelerix, including a stiff articulation with the ectotympanic, is a consistent feature of other mammals that do not hear frequencies below 400Hz.

Real Time Precursor Calculation for the Early Detection of Combustion Instabilities

Abstract The proper control of the pressure fluctuations inside the gas turbine combustors is becoming a key factor to contain the pollutant emissions and extend their operability limits, as a consequence of the leaner and leaner mixture the engines have to operate with. In this context, the mitigation of the combustion instabilities through active control strategies is nowadays taking more and more benefits from the most advanced data science techniques. The employment of such algorithms has not only the aim to detect an instability and bring the engine to operate in a stable window but, more and more often, to anticipate the rising of a dominant frequency in an early stage of growth, with advantages in terms of extension of the life of the mechanical components and, more importantly, the reduction of the number of startups. In this context, the present papers presents a reduced order model derived from the dynamic mode decomposition (DMD) algorithm that can be applied to analyze the time signals acquired by the pressure probes installed in a generic gas turbine combustor. The most useful information that are retrieved from the signal are the frequency content and the corresponding growth rate (GR). The latter parameter can be assumed to act like a precursor of the system instability, enabling the possibility to identify a potential issue well in advance with respect to the traditional approaches. This new method can pave the way to new control strategies, depending on the different kind of instabilities detected. Also these aspects will be addressed along this work, focusing the discussion on both thermo-acoustic instabilities and low-frequency tones associated with the flame extinction. Moreover, additional criteria that could be implemented along a control system based on this new methodology will be provided.

Modulation masking produced by a low-frequency pure tone

An intense low-frequency tone can affect the perception of amplitude modulation (AM) applied to a high-frequency carrier. Here, thresholds for detecting AM of a 3000-Hz carrier were measured in the presence of a 50-Hz pure tone at 91 dB SPL. When the carrier was presented at 20 dB sensation level (SL), the thresholds were higher than in the absence of the 50-Hz tone, increased when the AM frequency was increased from 20 to 100 Hz, and did not show a maximum near 50 Hz, as would be expected if the effect of the 50-Hz tone resulted from modulation detection interference. When the AM frequency was fixed at 50 Hz, the AM detection thresholds showed a minimum when the phase of the AM was 90° ahead of the phase of the 50-Hz tone (denoted Δφ = 90°) and a maximum for Δφ = 270°. To assess the role of the outer hair cells (OHCs), AM detection thresholds were measured as a function of Δφ using SLs of 20 and 50 dB for normal-hearing participants and 20 dB for hearing-impaired participants. It was assumed that the latter would have impaired OHC function. The pattern of the results was similar across SLs and groups: AM detection thresholds were 8–10 dB lower for Δφ = 90° than for Δφ = 270° in all cases. This suggests that the OHCs do not play a large role in these effects and supports the idea that the low-frequency tone biases the responses of inner hair cells tuned to high frequencies.

Band-pass filtering analysis on low-frequency tonal noise generated from a Krueger storage cavity

With the aim of investigating noise characteristics of tonal noise generated from a Krueger storage cavity, aero-acoustic experiments on a two-dimensional, Krueger flap configuration with an open or closed gap were conducted in the D5 aero-acoustic wind tunnel at Beihang University. The angles of attack are from 4° to 8°, and the free-stream velocities are from 45 m/s to 60 m/s. To study further the noise temporal characteristics and generation mechanism, experimental results were analyzed using a band-pass filtering method. The results show that low-frequency noise generated by the Krueger storage flow is dominant when the Krueger flap is deployed without a gap. For the Krueger configuration with a closed gap, low-frequency multiple tones observed at a free-stream velocity above 45 m/s are generated by self-excited oscillation within the storage cavity. The frequencies corresponding to these tonal noises have an octave relationship and satisfy the Strouhal number related scaling law. Filtering results reveal further that these low-frequency tones are intermittently and alternately excited in time and satisfy the oscillation mode switching mechanism.

Is Characteristic Frequency Limiting Real-Time Electrocochleography During Cochlear Implantation?

ObjectivesElectrocochleography (ECochG) recordings during cochlear implantation have shown promise in estimating the impact on residual hearing. The purpose of the study was (1) to determine whether a 250-Hz stimulus is superior to 500-Hz in detecting residual hearing decrement and if so; (2) to evaluate whether crossing the 500-Hz tonotopic, characteristic frequency (CF) place partly explains the problems experienced using 500-Hz.DesignMultifrequency ECochG comprising an alternating, interleaved acoustic complex of 250- and 500-Hz stimuli was used to elicit cochlear microphonics (CMs) during insertion. The largest ECochG drops (≥30% reduction in CM) were identified. After insertion, ECochG responses were measured using the individual electrodes along the array for both 250- and 500-Hz stimuli. Univariate regression was used to predict whether 250- or 500-Hz CM drops explained low-frequency pure tone average (LFPTA; 125-, 250-, and 500-Hz) shift at 1-month post-activation. Postoperative CT scans were performed to evaluate cochlear size and angular insertion depth.ResultsFor perimodiolar insertions (N = 34), there was a stronger linear correlation between the largest ECochG drop using 250-Hz stimulus and LFPTA shift (r = 0.58), compared to 500-Hz (r = 0.31). The 250- and 500-Hz CM insertion tracings showed an amplitude peak at two different locations, with the 500-Hz peak occurring earlier in most cases than the 250-Hz peak, consistent with tonotopicity. When using the entire array for recordings after insertion, a maximum 500-Hz response was observed 2–6 electrodes basal to the most-apical electrode in 20 cases (58.9%). For insertions where the apical insertion angle is >350 degrees and the cochlear diameter is <9.5 mm, the maximum 500-Hz ECochG response may occur at the non-apical most electrode. For lateral wall insertions (N = 14), the maximum 250- and 500-Hz CM response occurred at the most-apical electrode in all but one case.ConclusionUsing 250-Hz stimulus for ECochG feedback during implantation is more predictive of hearing preservation than 500-Hz. This is due to the electrode passing the 500-Hz CF during insertion which may be misidentified as intracochlear trauma; this is particularly important in subjects with smaller cochlear diameters and deeper insertions. Multifrequency ECochG can be used to differentiate between trauma and advancement of the apical electrode beyond the CF.

Rumbling, humming, booming – Perception of vehicle interior noise at low engine speeds

The reduction of fuel consumption of vehicles with combustion engines is a primary goal during the development of new vehicles. One approach to lower the fuel consumption is to reduce the engine speed. This changes the engine sound. Among others, low-frequency tonal components become audible. Sensations that are commonly associated with the perception of engine sounds with low-frequency tonal components are rumbling, humming and booming. Rumbling is characterized by a low-frequency tone that is amplitude modulated over time. Humming is elicited by an unmodulated low-frequency tone. The sensation of booming is an interaction of a low-frequency tone and modulated higher-frequency components. It is generally assumed that all these sensations have a negative impact on the pleasantness of the vehicle passengers, as they can cause tiredness and nausea. The present study investigates the influence of the stimulus characteristics on the above-mentioned sensations and the impact on the perceived pleasantness using psychoacoustic experiments. To explain the different sensations, artificial prototypical sounds were presented to the listeners prior to the experiment, which contained key stimulus properties for each sensation. The sensations were measured for recordings of vehicle interior sounds that were artificially manipulated to change the strength of the sensations. It is shown that not only the sensations change substantially but also the pleasantness, confirming a strong link between the sensations and pleasantness ratings. The results can form a basis for modeling these sensations and their impact on the pleasantness.