Frontal Horizontal Plane Research Articles

Localization of real and tangent-law panned phantom sound sources in the frontal horizontal plane

Auditory source separations of as little as 1 degree are detectable. However, presenting auditory stimuli at small separations presents technical challenges, with loudspeaker separation limited by transducer diameter. An alternative procedure is to utilize phantom sources, with the perceived position of a single source determined by the relative output levels of two spatially separated loudspeakers. Therefore, it is important to determine whether real and phantom sources can be localized with the same precision. In the present experiment, listeners localized real (individual) sources and phantom sources computed using a tangent-law model giving the same nominal azimuthal angles as the real sources. Listeners used a laser pointer to indicate perceived source location. Infrared cameras detected pointer position with responses stored in terms of azimuth. Signals were broadband or narrowband (300-700 Hz and 3800–4200 Hz) noise, 100 or 500 ms in duration. Generally, phantom sources were localized with less precision than real sources, and high-frequency signals were localized with less precision than broadband or low-frequency signals, with no effect of duration. Results show that phantom sources are localized with sufficient accuracy and precision to be useful in assessing auditory spatial acuity, but they are not localized with the same precision as real sources.

Performance on a spatially selective auditory attention listening task for sources in the horizontal or coronal planes

Listeners can use spatially selective auditory attention (SSAA) to focus on one talker in a complex acoustic scene. SSAA has been primarily investigated with targets and distractors arrayed in the frontal horizontal plane. In this study we compared normally hearing human listeners' performance on static and dynamic SSAA tasks in a frontal target/distractor configuration to performance with sources arrayed in either the rear horizontal plane, the overhead coronal plane, or the “underhead” coronal plane, all of which provide similar binaural difference cues with which to differentiate target and distractor locations. To achieve the coronal plane configurations, the listener's head was tipped forward to align the normally vertical axis with the horizontal plane. In the SSAA task, listeners attempted to report a 4-digit sequence of spoken digits from the target location while ignoring two simultaneous equal-intensity sequences spoken by the same talker presented from flanking loudspeakers separated by ±22.5° from the target. Listeners either held their head still (static conditions) with the front (horizontal configurations) or top (coronal configurations) of the head oriented toward 0 azimuth, or were oscillated passively at ∼0.14 Hz with an amplitude of ±45 degrees about the vertical axis (dynamic conditions).

Analysis and Experiment on the Limitations of Static and Dynamic Transaural Reproduction with Two Frontal Loudspeakers

By duplicating the binaural pressures of an actual source, transaural reproduction with two frontal loudspeakers is expected to recreate a virtual source in arbitrary direction. However, experiments indicated that in static transaural reproduction, the perceived virtual source is usually limited to the frontalhorizontal plane. The reasons for this limitation, as guessed, are that, in static reproduction, the dynamic cues for front-back and vertical localisation are incorrect, and the high-frequency spectral cues are unstable with head movement. To validate this hypothesis, the variations of ITD (interaural time difference) caused by head turning in both static and dynamic transaural reproductions are analysed. The results indicate that dynamic reproduction is able to create appropriate low-frequency ITD variations, and the static transaural reproduction is unable to do so. Psychoacoustic experiments are conducted to compare virtual source localisation in static and dynamic reproductions. The results indicate that dynamic reproduction is able to recreate the front, back, and vertical virtual source for low-pass stimuli below 3 kHz, while for full audible bandwidth stimulus, appropriate low-frequency dynamic cue and unstable high-frequency spectral cues in dynamic reproduction result in two splitting virtual sources.

Analysis of binaural sound pressure control and virtual source characteristics in stereophonic reproduction

In stereophonic reproduction, the manipulation of relative magnitude and phase between two loudspeakers enables to create virtual sources within an azimuth region in frontal–horizontal plane. The law of sine, which is based on evaluating the interaural phase difference and a conventional method for stereophonic analysis at low frequencies, fails to explain some characteristic in stereophonic reproduction, including the influence of span angle of loudspeakers on virtual source localization and the stability of virtual source created by out-of-phase loudspeaker signals. Analogy to the method in active sound control, an alternative method for analyzing the characteristics of virtual source in stereophonic reproduction is presented in this work. On the basis of shadowless head model at low frequency, the power effort of loudspeaker signals for creating virtual source in stereophonic reproduction is evaluated. The results indicate that for frontal virtual source within the span of loudspeakers, the power effort of in-phase loudspeaker signals increases with the increase in the span angle of loudspeakers. For lateral virtual source outside the span of loudspeakers, the power effort of out-of-phase loudspeaker signals increases with the target azimuth of virtual source. Increase in power effort makes the control of binaural pressures difficulty and, thus, virtual source instable.

Impact of processing-latency induced interaural delay and level discrepancy on sensitivity to interaural level differences in cochlear implant users.

This study investigated whether an interaural delay, e.g. caused by the processing latency of a hearing device, can affect sensitivity to interaural level differences (ILDs) in normal hearing subjects or cochlear implant (CI) users with contralateral normal hearing (SSD-CI). Sensitivity to ILD was measured in 10SSD-CI subjects and in 24normal hearing subjects. The stimulus was a noise burst presented via headphones and via a direct cable connection (CI). ILD sensitivity was measured for different interaural delays in the range induced by hearing devices. ILD sensitivity was correlated with results obtained in a sound localization task using seven loudspeakers in the frontal horizontal plane. In the normal hearing subjects the sensitivity to interaural level differences deteriorated significantly with increasing interaural delays. In the CI group, no significant effect of interaural delays on ILD sensitivity was found. The NH subjects were significantly more sensitive to ILDs. The mean localization error in the CI group was 10.8° higher than in the normal hearing group. No correlation between sound localization ability and ILD sensitivity was found. Interaural delays influence the perception of ILDs. For normal hearing subjects a significant decrement in sensitivity to ILD was measured. The effect could not be confirmed in the tested SSD-CI group, probably due to a small subject group with large variations. The temporal matching of the two sides may be beneficial for ILD processing and thus sound localization for CI patients. However, further studies are needed for verification.

Spatial speech detection for binaural hearing aids using deep phoneme classifiers.

Current hearing aids are limited with respect to speech-specific optimization for spatial sound sources to perform speech enhancement. In this study, we therefore propose an approach for spatial detection of speech based on sound source localization and blind optimization of speech enhancement for binaural hearing aids. We have combined an estimator for the direction of arrival (DOA), featuring high spatial resolution but no specialization to speech, with a measure of speech quality with low spatial resolution obtained after directional filtering. The DOA estimator provides spatial sound source probability in the frontal horizontal plane. The measure of speech quality is based on phoneme representations obtained from a deep neural network, which is part of a hybrid automatic speech recognition (ASR) system. Three ASR-based speech quality measures (ASQM) are explored: entropy, mean temporal distance (M-Measure), matched phoneme (MaP) filtering. We tested the approach in four acoustic scenes with one speaker and either a localized or a diffuse noise source at various signal-to-noise ratios (SNR) in anechoic or reverberant conditions. The effects of incorrect spatial filtering and noise were analyzed. We show that two of the three ASQMs (M-Measure, MaP filtering) are suited to reliably identify the speech target in different conditions. The system is not adapted to the environment and does not require a-priori information about the acoustic scene or a reference signal to estimate the quality of the enhanced speech signal. Nevertheless, our approach performs well in all acoustic scenes tested and varying SNRs and reliably detects incorrect spatial filtering angles.

Auditory model-based estimation of the effect of head-worn devices on frontal horizontal localisation

Auditory localisation accuracy may be degraded when a head-worn device (HWD), such as a helmet or hearing protector, is used. A computational method is proposed in this study for estimating how horizontal plane localisation is impaired by a HWD through distortions of interaural cues. Head-related impulse responses (HRIRs) of different HWDs were measured with a KEMAR and a binaural auditory model was used to compute interaural cues from HRIR-convolved noise bursts. A shallow neural network (NN) was trained with data from a subjective listening experiment, where horizontal plane localisation was assessed while wearing different HWDs. Interaural cues were used as features to estimate perceived direction and position uncertainty (standard deviation) of a sound source in the horizontal plane with the NN. The NN predicted the position uncertainty of localisation among subjects for a given HWD with an average estimation error of 1°. The obtained results suggest that it is possible to predict the degradation of localisation ability for specific HWDs in the frontal horizontal plane using the method.

Enhancement of interaural level differences for bilateral cochlear implant users

Bilateral cochlear implant (BiCI) users do not localize sounds as well as normal hearing (NH) listeners do. NH listeners rely on two binaural cues to localize sounds in the horizontal plane, namely interaural level differences (ILDs) and interaural time differences. BiCI systems, however, convey these cues poorly. In this work, we investigated two methods to improve the coding of ILDs in BiCIs. The first method enhances ILDs by applying an artificial current-versus-angle function to the clinical levels delivered by the basal electrodes of the CI contralateral to the target sound. The second method enhances ILDs by using bilaterally linked N-of-M band selection. Results indicate that the participants were able to discriminate the location of the sound more accurately at narrow azimuths when the ILD enhancement was applied, compared to when they were using natural ILDs. Also, the results show that linking the band selection had a positive effect on left/right discrimination accuracy at larger azimuths for three out of the 10 tested participants, when compared to unlinked band selection. Based on these results, we conclude that ILD enhancement besides linked N-of-M band selection can help some BiCI participants to discriminate sound sources on the frontal horizontal plane.

Children With Congenital Unilateral Sensorineural Hearing Loss: Effects of Late Hearing Aid Amplification-A Pilot Study.

Although children with unilateral hearing loss (uHL) have high risk of experiencing academic difficulties, speech-language delays, poor sound localization, and speech recognition in noise, studies on hearing aid (HA) outcomes are few. Consequently, it is unknown when and how amplification is optimally provided. The aim was to study whether children with mild-to-moderate congenital unilateral sensorineural hearing loss (uSNHL) benefit from HAs. All 6- to 11-year-old children with nonsyndromic congenital uSNHL and at least 6 months of HA use were invited (born in Stockholm county council, n = 7). Participants were 6 children (9.7- to 10.8-years-old) with late HA fittings (>4.8 years of age). Unaided and aided hearing was studied with a comprehensive test battery in a within-subject design. Questionnaires were used to study overall hearing performance and disability. Sound localization accuracy (SLA) and speech recognition thresholds (SRTs) in competing speech were measured in sound field to study hearing under demanding listening conditions. SLA was measured by recording eye-gaze in response to auditory-visual stimuli presented from 12 loudspeaker-video display pairs arranged equidistantly within ±55° in the frontal horizontal plane. The SRTs were measured for target sentences at 0° in spatially separated (±30° and ±150°) continuous speech. Auditory brainstem responses (ABRs) were obtained in both ears separately to study auditory nerve function at the brainstem level. The mean ± SD pure-tone average (0.5, 1, 2, and 4 kHz) was 45 ± 8 dB HL and 6 ± 4 dB HL in the impaired and normal hearing ear, respectively (n = 6). Horizontal SLA was significantly poorer in the aided compared with unaided condition. A significant relationship was found between aided SLA (quantified by an error index) and the impaired ear's ABR I to V interval, suggesting a relationship between the two. Results from questionnaires revealed aided benefit in one-to-one communication, whereas no significant benefit was found for communication in background noise or reverberation. No aided benefit was found for the SRTs in competing speech. Children with congenital uSNHL benefit from late HA intervention in one-to-one communication but not in demanding listening situations, and there is a risk of degraded SLA. The results indicate that neural transmission time from the impaired cochlea to the upper brainstem may have an important role in unilaterally aided spatial hearing, warranting further study in children with uHL receiving early HA intervention.

Reducing the Device Delay Mismatch Can Improve Sound Localization in Bimodal Cochlear Implant/Hearing-Aid Users.

In users of a cochlear implant (CI) together with a contralateral hearing aid (HA), so-called bimodal listeners, differences in processing latencies between digital HA and CI up to 9 ms constantly superimpose interaural time differences. In the present study, the effect of this device delay mismatch on sound localization accuracy was investigated. For this purpose, localization accuracy in the frontal horizontal plane was measured with the original and minimized device delay mismatch. The reduction was achieved by delaying the CI stimulation according to the delay of the individually worn HA. For this, a portable, programmable, battery-powered delay line based on a ring buffer running on a microcontroller was designed and assembled. After an acclimatization period to the delayed CI stimulation of 1 hr, the nine bimodal study participants showed a highly significant improvement in localization accuracy of 11.6% compared with the everyday situation without the delay line (p < .01). Concluding, delaying CI stimulation to minimize the device delay mismatch seems to be a promising method to increase sound localization accuracy in bimodal listeners.

Effects of Binaural Spatialization in Wireless Microphone Systems for Hearing Aids on Normal-Hearing and Hearing-Impaired Listeners.

Little is known about the perception of artificial spatial hearing by hearing-impaired subjects. The purpose of this study was to investigate how listeners with hearing disorders perceived the effect of a spatialization feature designed for wireless microphone systems. Forty listeners took part in the experiments. They were arranged in four groups: normal-hearing, moderate, severe, and profound hearing loss. Their performance in terms of speech understanding and speaker localization was assessed with diotic and binaural stimuli. The results of the speech intelligibility experiment revealed that the subjects presenting a moderate or severe hearing impairment better understood speech with the spatialization feature. Thus, it was demonstrated that the conventional diotic binaural summation operated by current wireless systems can be transformed to reproduce the spatial cues required to localize the speaker, without any loss of intelligibility. The speaker localization experiment showed that a majority of the hearing-impaired listeners had similar performance with natural and artificial spatial hearing, contrary to the normal-hearing listeners. This suggests that certain subjects with hearing impairment preserve their localization abilities with approximated generic head-related transfer functions in the frontal horizontal plane.

Combined Effects of Noise and Reverberation on Sound Localization for Listeners With Normal Hearing and Bilateral Cochlear Implants.

This study examined the individual and combined effects of noise and reverberation on the ability of listeners with normal hearing (NH) and with bilateral cochlear implants (BCIs) to localize speech. Six adults with BCIs and 10 with NH participated. All subjects completed a virtual localization test in quiet and at 0-, -4-, and -8-dB signal-to-noise ratios (SNRs) in simulated anechoic and reverberant (0.2-, 0.6-, and 0.9-s RT60) environments. BCI users were also tested at +8- and +4-dB SNR. A 3-word phrase was presented at 70 dB SPL from 9 simulated locations in the frontal horizontal plane (±90°), with the noise source at 0°. BCIs users had significantly poorer localization than listeners with NH in all conditions. BCI users' performance started to decrease at a higher SNR (+4 dB) and shorter RT60 (0.2 s) than listeners with NH (-4 dB and 0.6 s). The combination of noise and reverberation began to degrade localization of BCI users at a higher SNR and a shorter RT60 than listeners with NH. The clear effect of noise and reverberation on the performance of BCI users provides information that should be useful for refining cochlear implant processing strategies and developing cochlear implant rehabilitation plans to optimize binaural benefit for BCI users in everyday listening situations.

Single-Sided Deafness: Impact of Cochlear Implantation on Speech Perception in Complex Noise and on Auditory Localization Accuracy.

To assess auditory localization accuracy and speech reception threshold (SRT) in complex noise conditions in adult patients with acquired single-sided deafness, after intervention with a cochlear implant (CI) in the deaf ear. Nonrandomized, open, prospective patient series. Tertiary referral university hospital. Eleven patients with late-onset single-sided deafness (SSD) and normal hearing in the unaffected ear, who received a CI. All patients were experienced CI users. Unilateral cochlear implantation. Speech perception was tested in a complex multitalker equivalent noise field consisting of multiple sound sources. Speech reception thresholds in noise were determined in aided (with CI) and unaided conditions. Localization accuracy was assessed in complete darkness. Acoustic stimuli were radiated by multiple loudspeakers distributed in the frontal horizontal plane between -60 and +60 degrees. In the aided condition, results show slightly improved speech reception scores compared with the unaided condition in most of the patients. For 8 of the 11 subjects, SRT was improved between 0.37 and 1.70 dB. Three of the 11 subjects showed deteriorations between 1.22 and 3.24 dB SRT. Median localization error decreased significantly by 12.9 degrees compared with the unaided condition. CI in single-sided deafness is an effective treatment to improve the auditory localization accuracy. Speech reception in complex noise conditions is improved to a lesser extent in 73% of the participating CI SSD patients. However, the absence of true binaural interaction effects (summation, squelch) impedes further improvements. The development of speech processing strategies that respect binaural interaction seems to be mandatory to advance speech perception in demanding listening situations in SSD patients.

Cochlear Implantation Improves Spatial Release From Masking and Restores Localization Abilities in Single-sided Deaf Patients.

Adult patients with acquired single-sided deafness (SSD) benefit from binaural hearing after cochlear implantation (CI). To spatially separate the signal of interest from noise is of utmost importance for the speech understanding in challenging listening situations. This ability, however, largely depends on binaural hearing. CI in acquired SSD restores hearing on the deaf ear. This study intended to test, if this is accompanied by a restoration of binaural functions of the auditory system. Eleven CI users with SSD and normal hearing to mild sensorineural hearing loss in the contralateral ear participated in this study. Speech reception thresholds (SRT) were obtained using the Oldenburg Sentence Test (OLSA) sentence test in competing two talker babble noise. To evaluate spatial release from masking, seven spatial configurations of speech and noise were used in a free field setup: noise originated from 0 degree, ±45 degrees and ±90 degrees incidence angles, whereas speech was either presented from the front or ±90 degrees. In addition, localization ability in the frontal horizontal plane was assessed with a 1 s Comité Consultatif International Téléphonique et Télégraphique (CCITT) noise stimulus using an array of nine equally spaced loudspeakers. All tests were conducted in acoustic normal hearing ear alone (AH) and aided conditions. In conditions with spatially separated signal and noise sources, significant benefit of the aided over the AH condition was observed, even when noise was presented from the AH side. Localization ability significantly improved in the aided condition. The present data demonstrates that spatial release from masking can be restored in patients with SSD using a cochlear implant.

Sound localization in the presence of multiple reflections using a binaurally integrated cross-correlation/auto-correlation mechanism.

A precedence effect model is described that can use a binaural signal to robustly localize a sound source in the presence of multiple reflections for the frontal horizontal plane. The model also estimates a room impulse response from a running binaural signal and determines the spatial locations and delays of early reflections, without any prior or additional knowledge of the source. A dual-layer cross-correlation/auto-correlation algorithm is used to determine the interaural time difference of the direct sound source component and to estimate a binaural activity pattern.

Corneal-Reflection Eye-Tracking Technique for the Assessment of Horizontal Sound Localization Accuracy from 6 Months of Age.

The evaluation of sound localization accuracy (SLA) requires precise behavioral responses from the listener. Such responses are not always possible to elicit in infants and young children, and procedures for the assessment of SLA are time consuming. The aim of this study was to develop a fast, valid, and objective method for the assessment of SLA from 6 months of age. To this end, pupil positions toward spatially distributed continuous auditory and visual stimuli were recorded. Twelve children (29 to 157 weeks of age) who passed the universal newborn hearing screening and eight adults (18 to 40 years of age) who had pure-tone thresholds ≤20 dB HL in both ears participated in this study. Horizontal SLA was measured in a sound field with 12 loudspeaker/display (LD)-pairs placed in an audiological test room at 10 degrees intervals in the frontal horizontal plane (±55 degrees azimuth). An ongoing auditory-visual stimulus was presented at 63 dB SPL(A) and shifted to randomized loudspeakers simultaneously with pauses of the visual stimulus. The visual stimulus was automatically reintroduced at the azimuth of the sounding loudspeaker after a sound-only period of 1.6 sec. A corneal-reflection eye-tracking technique allowed the acquisition of the subjects' pupil positions relative to the LD-pairs. The perceived azimuth was defined as the median of the intersections between gaze and LD-pairs during the final 500 msec of the sound-only period. Overall SLA was quantified by an Error Index (EI), where EI = 0 corresponded to perfect match between perceived and presented azimuths, whereas EI = 1 corresponded to chance. SLA was rapidly measured in children (mean = 168 sec, n = 12) and adults (mean = 162 sec, n = 8). Visual inspection of gaze data indicated that gaze shifts occurred in sound-only periods. The medians of the perceived sound-source azimuths either coincided with the presenting sound-source azimuth or were offset by a maximum of 20 degrees in children. In contrast, adults revealed a perfect match from -55 to 55 degrees, except at 15 degrees azimuth (median = 20 degrees), with 9/12 of the quartile ranges = 0 degrees. Children showed a mean (SD) EI of 0.42 (0.17), which was significantly higher than that in adults (p < 0.0001). However, children revealed a distinct age-related EI improvement of 16 percentage points per year (r = -0.68, p = 0.015, n = 12), suggesting an ongoing maturation of SLA in the studied age range (29 to 157 weeks). The eight adults showed high SLA and high reliability as demonstrated by the low mean (SD) EI (0.054 [0.021]) and the low variability in test-retest differences (95% confidence interval = -0.020 to 0.046). Corneal-reflection eye-tracking provides an objective and fast assessment of horizontal SLA from about 6 months of age and may enable gaze to be used as an objective measure for sound localization in this age group. Infant SLA is immature and improvements are related to increasing age. Adults show high overall SLA and low intra- and intersubject variability in SLA. The technique may be used as a clinical tool for the evaluation of very early intervention in a young, preverbal population and throughout the life span.

Effects of Reverberation on Sound Localization for Bilateral Cochlear Implant Users

The purpose of this study was to examine the effects of reverberation on the ability of listeners with bilateral cochlear implants (BCIs) to localize speech in anechoic and reverberant environments. Two specific research questions were addressed: (1) how do listeners with BCIs localize sounds in different environments compared to listeners with normal hearing (NH)? and (2) at what reverberation time (RT60) does localization performance begin to decline for both groups of subjects? Six adults with BCIs and ten with NH participated. All subjects completed a virtual localization test in simulated anechoic and reverberant environments (0.0, 0.2, 0.6, and 0.9 s RT60) in quiet. A three-word phrase was presented at 70 dBSPL from nine simulated source locations in the frontal-horizontal plane (± 900). Root-mean-square localization error (RMSLE) in degrees was calculated. Results revealed localization accuracy significantly decreased as reverberation time increased for both groups of subjects. Listeners with BCIs had significantly poorer localization accuracy than listeners with NH in all conditions. Their RMSLE changed from 320 in anechoic condition to 600 in RT60 0.9s condition, while corresponding change for listeners with NH was only from 170 to 220. In addition, localization performance of listeners with BCIs started to decrease at a shorter reverberation time (RT60 0.6s) compared to those with NH (RT60 0.9s). In conclusion, reverberation significantly degraded localization performance, with a greater influence on listeners with BCIs than listeners with NH. In addition, bilateral experience is likely to help listeners with BCIs achieve a better localization outcome over time. It is important to apply the information obtained in this study to optimize binaural benefit for listeners with BCIs in everyday listening situations.

Sound Source Localization by Hearing Preservation Patients with and without Symmetrical Low-Frequency Acoustic Hearing

The aim of this article was to study sound source localization by cochlear implant (CI) listeners with low-frequency (LF) acoustic hearing in both the operated ear and in the contralateral ear. Eight CI listeners had symmetrical LF acoustic hearing and 4 had asymmetrical LF acoustic hearing. The effects of two variables were assessed: (i) the symmetry of the LF thresholds in the two ears and (ii) the presence/absence of bilateral acoustic amplification. Stimuli consisted of low-pass, high-pass, and wideband noise bursts presented in the frontal horizontal plane. Localization accuracy was 23° of error for the symmetrical listeners and 76° of error for the asymmetrical listeners. The presence of a unilateral CI used in conjunction with bilateral LF acoustic hearing does not impair sound source localization accuracy, but amplification for acoustic hearing can be detrimental to sound source localization accuracy.

Sound source localization from tactile aids for unilateral cochlear implant users

The present research asks whether two tactile aids with directional microphones, by providing additional inter-channel level information and etc., could help unilateral cochlear implant (CI) localize sound sources. For normal hearing subjects, sound source localization based on tactile vibration cues alone can be as accurate as auditory localization in the frontal horizontal plane (Gescheider, 1970). CI users may as well benefit from additional tactile aids just as normal hearing people do. The current study uses two bone-anchored hearing aids (BAHA) as sources of tactile vibration. The two BAHAs, bonded together by a special gadget to maintain a particular distance and angle, both have directional microphones, and are programed so that one point to the front-left side and the other to the front-right side. Unilateral CI users voluntarily participated in the experimental study. Wide band noise stimuli were presented at 65 dB SPL. The subjects hold one BAHA in each hand and do localization tasks with (1) CI only and (2) with CI and tactile sensation combined. Preliminary data shows CI users can get some benefit from the additional information provided by tactile aids in 360 degree localization (45 degree spacing) on the horizontal plane.

Age-related deterioration of the representation of space in human auditory cortex

One of the principal auditory disabilities associated with older age is difficulty in locating and tracking sources of sound. This study investigated whether these difficulties are associated with deterioration in the representation of space in the auditory cortex. In psychophysical tests, half of a group of older (>60 years) adults displayed spatial acuity similar to that of young adults throughout the frontal horizontal plane. The remaining half had considerably poorer spatial acuity at the more peripheral regions of frontal space. Computational modeling of electroencephalographic responses to abrupt location shifts demonstrated marked differences in the spatial tuning of populations of cortical neurons between the older adults with poor spatial acuity on the one hand, and those with good spatial acuity, as well as young adults, on the other hand. In those with poor spatial acuity, cortical responses contained little information with which to distinguish peripheral locations. We demonstrate a clear link between neural responses and spatial acuity measured behaviorally, and provide evidence for age-related changes in the coding of horizontal space.