Jeffrey J. DiGiovanni

Basilar membrane nonlinearity and loudness

Loudness matching functions for tones for persons with one shifted-threshold ear (hearing loss and noise-shifted thresholds) and one ear within normal limits were used to derive the presumed basilar membrane (BM) input-output (I/O) function in a normal ear. The comparison was made by assuming that the BM I/O function for the ear with the cochlear threshold shift has a slope of one (a linearized cochlea). The function for the normal ear was derived from the loudness matching function based on this assumption. Comparisons were made for archival basilar membrane data [M. A. Ruggero, N. C. Rich, A. Recio, S. S. Narayan, and L. Robles, J. Acoust. Soc. Am. 101, 2151-2163 (1997)] for chinchilla and archival loudness matches for long-duration tones for persons with various degrees of cochlear hearing loss [F. Miskolczy-Fodor, J. Acoust Soc. Am. 32, 486-492 (1960)]. Comparisons were made also between BM I/O functions and ones derived from loudness matches for persons with unilateral hearing loss simulated by broadband noise. The results show a close resemblance between the basilar membrane I/O function and the function derived from loudness matches for long-duration tones, even though the comparison was between human and chinchilla data. As the degree of threshold shift increases from 40 to 80 dB, the derived BM I/O functions become shallower, with slopes for losses of 60 dB or more falling in the range of values reported for physiological data. Additional measures with short-duration tones in noise show that the slope of the loudness function and the slope of the derived basilar membrane I/O function are associated with the behavioral threshold for the tone. The results for long-duration tones suggest a correspondence between BM displacement and loudness perception in cases of recruitment, but the relation between the degree of loss and the amount of BM compression and the relation between signal duration and compression suggests that other factors, such as the neural population response, may play a role.

Masker laterality and cueing in forward-masked intensity discrimination

Forward-masked intensity discrimination was measured as a function of level in experiments designed to reveal insights into the mechanism(s) underlying the midlevel elevation of the Weber fraction. The standard and maskers were 1.0-kHz tones that were separated by 100 ms. Performance was measured for listeners with normal hearing using an adaptive procedure. In experiment 1, intensity discrimination was measured in the presence of an ipsilateral masker (80 dB SPL), a contralateral masker (93 dB SPL), and a binaural (dichotic) masker produced by combining the ipsilateral and contralateral maskers. Listeners perceived only the contralateral masker in the binaural-masker condition. The contralateral masker produced a small midlevel elevation of the Weber fraction. The ipsilateral masker and the binaural masker produced a large, midlevel elevation of the Weber fraction. Experiment 2 found that a two-tone masker resulted in a reduction (improvement) in the Weber fraction for some conditions, but the midlevel elevation remained for all subjects in this cue-tone condition. Experiment 3 demonstrated that cross talk could not account for all of the masking observed with contralateral maskers. Taken together, the results suggest that a single complex mechanism or multiple mechanisms may be responsible for the masking seen in these experiments. On the basis of the cueing results, it is concluded that a portion of the masking is due to cognitive factors; however, a sensory mechanism cannot be ruled out for the remaining portion, based on the results of these experiments. Finally, a small but significant amount of masking due to contralateral maskers places the mechanism for this outcome central to the cochlear nucleus.

Effects of recurrent tonal information on auditory working memory for pitch

This study ascertained the influence of repeating pitch information within an intervening tonal sequence upon the extent of interference for a pitch standard held within auditory working memory as measured by the difference limen for frequency (DLF). Standard and comparison tones were presented to subjects and same/different responses were obtained using a touch screen monitor and the DLF was measured using single interval adjustment matrix (SIAM) procedure [Kaernbach, C., 1990. A single-interval adjustment-matrix (SIAM) procedure for unbiased adaptive testing. J. Acoust. Soc. Am. 88, 2645-2655]. Estimates of the DLF were obtained in a control condition with a silent inter-comparison interval and three conditions containing intervening tones within the temporal gap between the standard and comparison stimuli. The presence of intervening stimuli produced a significant increase in the DLF when the intervening tonal sequence contained tones with pitches that differed from that of the standard (Int condition) as well as when the sequence contained a tone with a pitch identical to that of the comparison (RptCmp condition). Further, the DLFs obtained for RptCmp condition were significantly higher than those measured in the Int condition. The DLFs measured in the condition where the pitch of an intervening tone was identical to the standard were significantly lower than those for the Int and RptCmp condition, but did not differ from the DLFs for the control condition. These results indicate that either a release from or an increase in interference in auditory working memory for pitch can occur dependent upon the frequency relationships between of the standard, comparison, and intervening tones.

Verification of in situ thresholds and integrated real-ear measurements.

BACKGROUND Accurate prescriptive gain results in a more accurate fit, lower return rate in hearing aids, and increased patient satisfaction. In situ threshold measurements can be used to determine required gain. The Widex Corporation uses an in situ threshold measurement strategy, called the Sensogram. Real-ear measurements determine if prescriptive gain targets have been achieved. Starkey Laboratories introduced an integrated real-ear measurement system in their hearing aids. PURPOSE To determine whether the responses obtained using the Widex Sensogram were equivalent to those obtained using current clinical threshold measurement methods. To determine the accuracy of the Starkey IREMS™ (Integrated Real Ear Measurement System) in measuring RECD (real-ear to coupler difference) values compared to a dedicated real-ear measurement system. RESEARCH DESIGN A verification design was employed by comparing participant data measured from standard, benchmark equipment and procedures against new techniques offered by hearing-aid manufacturers. STUDY SAMPLE A total of 20 participants participated in this study. Ten participants with sensorineural hearing loss were recruited from the Ohio University Hearing, Speech, and Language Clinic participated in the first experiment. Ten participants with normal hearing were recruited from the student population at Ohio University participated in both experiments. The normal-hearing group had thresholds of 15 dB HL or better at the octave frequencies of 250-8000 Hz. The hearing-impaired group had thresholds of varying degrees and configurations with thresholds equal to or poorer than 25 dB HL three-frequency pure-tone average. DATA COLLECTION AND ANALYSIS The order of measurement method for both experiments was counterbalanced. In Experiment 1, thresholds obtained via the Widex Sensogram were compared to thresholds obtained for each participant using a clinical audiometer and ER-3A insert ear phones. In Experiment 2, RECD values obtained via the Starkey IREMS were compared to RECD values obtained via the Audioscan Verifit™. A repeated-measures analysis of variance (ANOVA) was used for statistical analysis, and a Fishers LSD (least significant difference) was used as a post hoc analysis tool. RESULTS A significant difference between Sensogram thresholds and conventional audiometric thresholds was found with the Sensogram method resulting in better threshold values at 0.5, 1.0, and 2.0 kHz for both groups. In Experiment 2, a significant difference between RECD values obtained by the Starkey IREMS and the Audioscan Verifit system was found with significant differences in RECD values found at 0.25, 0.5, 0.75, 1.5, 2.0, and 6.0 kHz. CONCLUSIONS The Sensogram data differ significantly from traditional audiometry at several frequencies important for speech intelligibility. Real-ear measures are still required for verification of prescribed gain, however, calling into question any claims of shortened fitting time. The Starkey IREMS does perform real-ear measurements that vary significantly from benchmark equipment. These technologies represent a positive direction in prescribing accurate gain during hearing-aid fittings, but a stand-alone system is still the preferred method for real-ear measurements in hearing-aid fittings.

Intensity discrimination of ramped and damped tones

Intensity discrimination of 1.0‐kHz tones that had exponentially ramped or damped envelopes was measured as a function of duration and level. Standard levels ranged from near threshold to 90 dB SPL and durations ranged from 10 to 200 ms. Just‐noticeable differences for some subjects were smaller for damped tones than for ramped tones for the same duration and level. For these conditions, damped tones showed more temporal integration than ramped tones. This result is somewhat surprising given that the subjective duration of ramped tones increased by a factor of 100 for stimuli ranging from 10 to 200 ms, whereas the subjective duration of damped tones increased by a much smaller factor of 28 over the same range of durations. Possible physiological and cognitive explanations for these differences will be discussed. [Work supported by NIH‐NIDCD R29 DC01542.]

Stapedial Reflex and Ears With High Static Acoustic Admittance

PURPOSE To evaluate modified acoustic reflex diagnostic protocols for a group of individuals (n = 9) with high peak compensated static acoustic admittance (Y(tm)) tympanograms. METHOD A modified procedure designed to improve acoustic stapedius reflex threshold (ASRT) measurements in individuals with high-admittance tympanograms was employed in both an experimental and a control group. ASRTs were measured at 0.5, 1.0, and 2.0 kHz, ipsilateral and contralateral. Measurements were obtained within each condition for 7 ear canal pressures that were set to 0, +/-50, +/-100, and +/-150 daPa (relative to tympanometric peak pressure [TPP]). RESULTS Though measuring ASRTs at -50 daPa (relative to TPP) in the high-admittance and normal groups did not result in significantly better thresholds than at TPP, the absent reflex rate was reduced when the ear canal pressure was changed by -50 daPa during ASRT measurements. CONCLUSIONS Based on this sample, it is suggested that a patient presenting with high peak compensated static acoustic admittance (peak Y(tm) > or = 2.1 mmho) undergo ASRT evaluation with the ear canal pressure set to -50 daPa (relative to TPP).

Do listeners include the echo portion of a damped sound when judging its duration

Ramped sounds (slow attack, fast decay) are perceived to be longer in duration than damped sounds (fast attack, slow decay) that are the same physical duration even when they are simply time‐reversed versions of each other. Stecker and Hafter [J. Acoust. Soc. Am. 107, 3358–3368 (2000)] suggest that this perceptual difference is a result of listeners ignoring a portion of the decay of damped sounds because they consider it an ‘‘echo.’’ To test this idea, a duration‐matching experiment with two groups of 10 listeners was completed. Each group matched the duration of a broadband noise to two natural sounds, a drum strike and a word spoken in a reverberant room, presented in the normal fashion and reversed in time. The first group was told to match the duration of the sounds. The second group was told to consider the entire duration of the sound, even portions that sound like an echo. The ratio of ramped/damped at equal subjective duration was larger for the first group than for the second group. This finding...

The impact of perilaryngeal vibration on the self-perception of loudness and the Lombard effect

The role of somatosensory feedback in speech and the perception of loudness was assessed in adults without speech or hearing disorders. Participants completed two tasks: loudness magnitude estimation of a short vowel and oral reading of a standard passage. Both tasks were carried out in each of three conditions: no-masking, auditory masking alone, and mixed auditory masking plus vibration of the perilaryngeal area. A Lombard effect was elicited in both masking conditions: speakers unconsciously increased vocal intensity. Perilaryngeal vibration further increased vocal intensity above what was observed for auditory masking alone. Both masking conditions affected fundamental frequency and the first formant frequency as well, but only vibration was associated with a significant change in the second formant frequency. An additional analysis of pure-tone thresholds found no difference in auditory thresholds between masking conditions. Taken together, these findings indicate that perilaryngeal vibration effectively masked somatosensory feedback, resulting in an enhanced Lombard effect (increased vocal intensity) that did not alter speakers’ self-perception of loudness. This implies that the Lombard effect results from a general sensorimotor process, rather than from a specific audio-vocal mechanism, and that the conscious self-monitoring of speech intensity is not directly based on either auditory or somatosensory feedback.

The Interprofessional Education Environment: Places and Pedagogies

Interprofessional education (IPE) can occur in many places and in many ways. In this article, we focus on the inclusion of standards from the Interprofessional Education Collaborative in several different environments. We consider traditional classrooms and classrooms that integrate clinical placements for varying amounts of instructional time. We also consider a various types of simulations, including virtual and augmented reality, and their potential for advancement of IPE.

Relationships among musical training and pitch matching in children and adults

This experiment attempted to determine if individuals with extensive musical training’s pitch perception and memory were more resistant to degradation (e.g., time and interference) than that of individuals with limited musical training. It is known that musical training influences cortical sound processing through learning-based processes, but also at the preattentive level within the brainstem. Pitch memory abilities were investigated in 66 participants with no known hearing, attention, or cognitive impairment. Participants were placed into subgroups based on age (young children, older children, and adults) and their self-reported musical training experience. Two experiments measuring auditory perception and memory skills for pitch were collected, the pitch pattern span (PPS; Weaver, DiGiovanni, & Ries, 2015) and a pitch matching retention task based on Ross, Olsen, and Gore’s procedure (2003). We found that individuals with greater musical training exhibited enhanced pitch perception and memory processe...