Sound localization cues generally include interaural time difference, interaural intensity difference, and spectral cues. The purpose of this study is to investigate the important spectral cues involved in so-called head related transfer functions (HRTFs) using a combination of HRTF analyses and a virtual sound localization (VSL) experiment. Previous psychoacoustical and physiological studies have both suggested the existence of spectral modulation frequency (SMF) channels for analyzing spectral information (e.g., the spectral cues coded in HRTFs). SMFs are in a domain related to the Fourier transform of HRTFs. The relationship between various SMF regions and sound localization was tested here by filtering or enhancing HRTFs in the SMF domain under a series of conditions using a VSL experiment. Present results revealed that azimuth localization was not significantly affected by HRTF manipulation. Applying notch filters between 0.1 and 0.4 cyclesoctave or between 0.35 and 0.65 cyclesoctave resulted in significantly less accurate elevation responses at low elevations, while spectral enhancement in these two SMF regions did not produce a significant change in sound localization. Likewise, low-pass filtering at 2 cyclesoctave did not significantly influence localization accuracy, suggesting that the major cues for sound localization are in the SMF region below 2 cyclesoctave.

Objectives: Lexical tone information provides redundant cues for the recognition of Mandarin sentences in listeners with normal hearing in quiet conditions. The contribution of lexical tones to Mandarin sentence recognition in listeners with hearing aids (HAs) is unclear. This study aimed to remove lexical tone information and examine the effects on Mandarin sentence intelligibility in HA users. The second objective was to investigate the contribution of cognitive abilities (i.e., general cognitive ability, working memory, and attention) on Mandarin sentence perception when the presentation of lexical tone information was mismatched. Design: A text-to-speech synthesis engine was used to manipulate Mandarin sentences into three test conditions: (1) a Normal Tone test condition, where no alterations were made to lexical tones within sentences; (2) a Flat Tone test condition, where lexical tones were all changed into tone 1 (i.e., the flat tone); and (3) a Random Tone test condition, where each word in test sentences was randomly assigned one of four Mandarin lexical tones. The manipulated sentence signals were presented to 32 listeners with HAs in both quiet and noisy environments at an 8 dB signal to noise ratio. Results: Speech intelligibility was reduced significantly (by approximately 40 percentage points) in the presence of mismatched lexical tone information in both quiet and noise. The difficulty in correctly identifying sentences with mismatched lexical tones among adults with hearing loss was significantly greater than that of adults with normal hearing. Cognitive function was not significantly related to a decline in speech recognition scores. Conclusions: Contextual and other phonemic cues (i.e., consonants and vowels) are inadequate for HA users to perceive sentences with mismatched lexical tone contours in quiet or noise. Also, HA users with better cognitive function could not compensate for the loss of lexical tone information. These results highlight the importance of accurately representing lexical tone information for Mandarin speakers using HAs.

The present study examined the change in spectral properties of Mandarin vowels and fricatives caused by nonlinear frequency compression (NLFC) used in hearing instruments and how these changes affect the perception of speech sounds in normal-hearing listeners. Speech materials, including a list of Mandarin monosyllables in the form of /dV/ (12 vowels) and /Ca/ (five fricatives), were recorded from 20 normal-hearing, native Mandarin-speaking adults (ten males and ten females). NLFC was based on Phonak SoundRecover algorithms. The speech materials were processed with six different NLFC parameter settings. Detailed acoustic analysis revealed that the high front vowel /i/ and certain compound vowels containing /i/ demonstrated positional deviation in certain processed conditions in comparison to the unprocessed condition. All five fricatives showed acoustic changes in spectral features in all processed conditions. Fourteen Mandarin-speaking, normal-hearing adult listeners performed phoneme recognition with the six NLFC processing conditions. When the cut-off frequency was set relatively low, recognition of /s/ was detrimentally affected, whereas none of the NLFC processing configurations affected the other phonemes. The discrepancy between the considerable acoustic changes and the negligible adverse effects on perceptual outcomes is partially accounted for by the phonology system and phonotactic constraints in Mandarin.

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Background Mandarin Chinese has a rich repertoire of high-frequency speech sounds. This may pose a remarkable challenge to hearing-impaired listeners who speak Mandarin Chinese because of their high-frequency sloping hearing loss. An adaptive nonlinear frequency compression (adaptive NLFC) algorithm has been implemented in contemporary hearing aids to alleviate the problem. Purpose The present study examined the performance of speech perception and sound-quality rating in Mandarin-speaking hearing-impaired listeners using hearing aids fitted with adaptive NLFC (i.e., SoundRecover2 or SR2) at different parameter settings. Research Design Hearing-impaired listeners' phoneme detection thresholds, speech reception thresholds, and sound-quality ratings were collected with various SR2 settings. Study Sample The participants included 15 Mandarin-speaking adults aged 32 to 84 years old who had symmetric sloping severe-to-profound sensorineural hearing loss. Intervention The participants were fitted bilaterally with Phonak Naida V90-SP hearing aids. Data Collection and Analysis The outcome measures included phoneme detection threshold using the Mandarin Phonak Phoneme Perception test, speech reception threshold using the Mandarin hearing in noise test (M-HINT), and sound-quality ratings on human speech in quiet and noise, bird chirps, and music in quiet. For each test, five experimental settings were applied and compared: SR2-off, SR2-weak, SR2-default, SR2-strong 1, and SR2-strong 2. Results The results showed that listeners performed significantly better with SR2-strong 1 and SR2-strong 2 settings than with SR2-off or SR2-weak settings for speech reception threshold and phoneme detection threshold. However, no significant improvement was observed in sound-quality ratings among different settings. Conclusions These preliminary findings suggested that the adaptive NLFC algorithm provides perceptual benefit to Mandarin-speaking people with severe-to-profound hearing loss.

The aim of this study was to evaluate the efficacy of dual compression for Mandarin-speaking hearing aid users. Dual compression combines fast and slow compressors operating simultaneously across all frequency channels. The study participants were 31 hearing aid users with symmetrical moderate-to-severe hearing loss, with a mean age of 67 years. A new pair of 20-channel behind-the-ear hearing aids (i.e., Phonak Bolero B90-P) was used during the testing. The results revealed a significant improvement in speech reception thresholds in noise when switching from fast-acting compression to dual compression. The sound quality ratings revealed that most listeners preferred dual compression to fast-acting compression for listening effort, listening comfort, speech clarity, and overall sound quality at +4 dB signal-to-noise ratio. These results are consistent with predictions based on the theoretical understanding of dual and fast-acting compression. However, whether these results can be generalized to other languages or other dual compression systems should be verified by future studies.

Background Tinnitus is a prevalent auditory disorder that can become severely debilitating. Despite decades of investigation, there remains no conclusive cure for tinnitus. Clinical practice guidelines (CPGs) are available for assessing and managing tinnitus. Even though such guidelines have been available for several years, the degree that audiologists adhere to them has remained unexplored. Purpose of Study To determine what clinical practices are commonly used by audiologists in the assessment and management of the patient population with tinnitus, we administered an online survey to audiologists practicing in the United States and Canada. Results Among the audiologists that completed the survey and were included in the final analysis (n = 61), 70% were from the United States and 30% were from Canada. The audiologists represented a wide range of clinical experience (1–35 years). On average, those who completed the survey were relatively confident in their ability to assess and manage tinnitus patients indicated by a 0 to 100 Likert scale, with 0 representing no confidence (mean 72.5, ± 21.5 standard deviation). The most commonly reported tinnitus assessment tools were pure tone audiogram (0.25–8 kHz), administration of standardized questionnaires, and tinnitus pitch and loudness matching. Approximately half (55%) of audiologists indicated they include otoacoustic emissions, while less audiologists (<40%) reported measuring high-frequency thresholds, minimum masking levels, or loudness discomfort levels. The most common recommendation for tinnitus patients was amplification (87%), followed by counseling (80%) and sound therapy (79%). Conclusion Few audiologists administer a truly comprehensive tinnitus assessment and ∼20% indicated not recommending counseling or sound therapy to manage tinnitus. The results are discussed in the context of what is explicitly indicated in published CPGs, professional organization recommendations, and recent findings of peer-reviewed literature.

Decision weights were estimated in a profile analysis task to determine whether onset asynchronies between the signal component and the nonsignal components encourage the segregation of the signal relative to the other components. The signal component onset was either synchronous or asynchronous with respect to the nonsignal components. In the asynchronous conditions, thresholds were higher and the decision weights were less efficient than in the synchronous conditions. These data are largely consistent with a segregation hypothesis: onset asynchrony encourages subjects to shift strategies from one of spectral shape discrimination toward one of intensity discrimination.