摘要:

Tests on supraaural‐ and insert‐type earphones for telephone applications, designed from measurements with real ears and the American National Standards Institute (ANSI) 2‐ and 6‐cm3calibration couplers, are reported. Disagreements between real‐ear and coupler data are rationalized by reducing the basic 2‐cm3volume to 1.3 cm3and employing an approximate transfer characteristic to relate the supraaural coupler data to a common plane of reference corresponding to the tympanum position. Several experimental couplers for obtaining data within the telephone speech band, which permit measurements on the two types of earphone at the common plane, are described.

ISSN:0001-4966    

DOI:10.1121/1.1913292

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

We compared postmasking recovery of click action potentials (APs) with that of click loudness in seven otologically normal subjects. The APs were recorded by averaging the pickup of a nonsurgically placed, external‐meatus electrode. We found that increasing masking duration slowed recovery of both click loudness and click AP amplitude. However, the rate of recovery of click loudness was much faster than the rate of recovery of click AP amplitude. There were order of magnitude differences between the effects of click attenuation and of masking on click microphonic and AP latency. It is therefore very unlikely that middle‐ear muscle contractions influenced the results. The relatively slow postmasking AP recovery (complete recovery requiring up to 500 msec) and the masking‐duration effect probably originate in the sensory end‐organ. These effects can therefore be regarded as manifestations of “sensory adaptation.” However, the comparatively rapid postmasking recovery of click loudness suggests that some form of (central?) compensation prevents subjective appreciation of auditory adaptation.

ISSN:0001-4966    

DOI:10.1121/1.1913293

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

Two experiments are reported upon the influence of a computer aid on the recognition of complex sounds. Twelve112‐htraining and test sessions were conducted over a period of two weeks. Measures of unaided listener performance (L), computer performance (C), and combined performance (C&L) were obtained. In Expt. 1 the reliability of the computer was varied, while audio signal‐to‐noise (S/N) ratio was kept constant. The results showed (1) that as C increases so (C&L) increase; (2) that excessively high C performance reduces the listeners performance; and (3) that the strategy involved in using the computer and audio displays tends to evolve with training. Initially, attempts to compromise between computer and audio information often lead to (C&L) performance lower than it need be if the poorer display had been ignored. Later, the more valid display tends to be relied upon and finally in certain instances an optimal strategy tends to emerge in which (C&L) performance is above both C and L. Experiment 2 compared “dependent” and “independent” systems. In the former condition audio and computer displays are fed to the same observer; in the independent condition one observer receives the audio imputs and a partner views the computer display and makes the final (C&L) decision. No major differences in overall preferences were observed, except that the independent condition yields poor L performance.

ISSN:0001-4966    

DOI:10.1121/1.1913294

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

Two of the basic requirements of an ear‐model design is that the transfer characteristic of the ear canal and the impedance as measured at the eardrum closely agree with results obtained on real ears. In the case of the electrical analog model, this requires that the number of sections that are used to represent the ear canal provide an upper cutoff well beyond the highest frequency under study. This is particularly true where the effect of ear‐canal taper is of interest. For these purposes, 10‐section analog networks of uniform and of tapered design were employed. For network representation of the eardrum and the adjacent connecting structures, the effectiveness of one‐, two‐, three‐, and four‐branch terminations were explored. Of these, the two‐ and the four‐branch analog networks were found to provide the best overall representations.

ISSN:0001-4966    

DOI:10.1121/1.1913295

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

The Peterson‐Bogert model of the cochlea [J. Acoust. Soc. Amer.22, 369–381 (1950)] specifies, as one of its boundary conditions, zero pressure at the round window. This specification is equivalent to eliminating the round‐window membrane. We have substituted a new boundary condition, representing the round‐window membrane with an acoustic stiffness. With the new boundary condition, the equation forp+(x) requires a new solution, and a new value ofp−(x) atx= 0 is needed. The solution forp+(x) and the necessary value ofp−(0) are given as a function of frequency for sinusoidal stimulation. The latter value is used as the input to the Peterson‐Bogert type of model of the basilar membrane. The model's input impedance as well as the relative displacement between the oval and round windows are also given. These relationships are compared with experimental findings.

ISSN:0001-4966    

DOI:10.1121/1.1913296

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

Discrimination tasks with a 500‐Hz tone and involving various combinations of binaural time and intensity cues were used to generate binaural discrimination spaces. The resultant spaces indicate that the sensations which arise from interaural time cues and interaural amplitude cues are correlated with a correlation coefficient of approximately 0.88; that is, a large fraction of the total sensation arising from one interaural cue will add or subtract as a scalar quantity with the sensation produced by the other interaural cue, but a residual sensation will always remain for all combinations of time and intensity cues. The same spatial framework provides a good description of the results of time intensity trading tasks. When applied to an MLD detection paradigm, this framework provides predictions which are in qualitative agreement with masking studies using tones and narrow‐band noise as maskers.

ISSN:0001-4966    

DOI:10.1121/1.1913297

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

Current methods of calculating proportion correct from the raw data of forced‐choice experiments involve obtaining the proportion of times that a given response was made, contingent upon the occurrence of the corresponding stimulus. Here, another method is introduced: obtaining the proportion of times that a given stimulus occurred, conditional upon the occurrence of the corresponding response. Both of these computational methods are examined with respect to their stability over variations of sensitivity, response bias, and stimulus bias.

ISSN:0001-4966    

DOI:10.1121/1.1913298

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

A combination of mathematical modeling techniques and computer simulation methods has been used for the interpretation of the behavior of the experimentally observed cochlear potentials. In particular, the models of the mechano‐acoustical system and of the electrical potential generating mechanism of the transducer cells have been derived in terms of state variables and of equivalent functional relationships, respectively. These formulations allow economical numerical solution of the complex equations which describe cochlear functions. Using these techniques we have been able to confirm that nonlinearity of the individual haircell output is compatible with the observed apparent linearity of the experimentally observed macroscopic CM (cochlear microphonic) potential and that effective low‐pass filtering reduces distortion in the measured potential waveform due to the interaction of the electrical outputs of the haircells along the basilar membrane. This filtering is not influenced to a great extent by the attenuation along the cochlea. Further filtering may also be contributed by the RC networks formed by the various membrane capacitances and resistances. Comparison of the experimental and simulated CM vs SPL functions (frequency as parameter) shows that a simple phase cancellation process is not sufficient, but that an additional mechanism must be postulated to account for the decrease of the CM at very high sound intensities; the IHC (internal haircell) output is assumed to be 20 dB less sensitive than the OHC (outer haircell) output and of opposite sign. A similar comparison for the CM amplitude, CM phase, and SP−amplitude as functions of frequency (SPL as parameter) also provides good agreement. Our results demonstrate that the particular behavior of the basilar membrane and the interference effect between haircell outputs account for the majority of electrical phenomena observed by the classical differential electrode method.

ISSN:0001-4966    

DOI:10.1121/1.1913299

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

We investigated the concept of a critical masking interval, the time period during which noise is effective in masking a brief signal. The signal was a 100‐μsec click temporally placed in the center of a gated‐noise masker. Both the click and the noise were low‐pass filtered so that the power spectra of signal and noise have similar shape. The duration of the noise masker was varied from 100 μsec to 300 msec and two noise levels were employed. Like the estimate of the critical bandwidth, the estimate of the critical masking interval can be made in two independent ways. First, for long durations of the noise masker, the ratio of click energy to overall noise power indicates that the critical masking interval is about 14 msec. Second, progressively shortening the duration of the noise masker did not improve detectability until the duration was less than approximately 10 msec. The near agreement of these two independent estimates supports our interpretation of the data in terms of the concept of a critical masking interval.

ISSN:0001-4966    

DOI:10.1121/1.1913300

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

Response patterns to click stimulation of 907 single cochlear nerve fibers, having characteristic frequencies below 2000 Hz, can be separated into two populations on the basis of salient features. Population I consists of approximately 93% of the fibers, and Population II consists of approximately 7% of the fibers. A statistical description of the correlation between properties of response patterns of Population I fibers and stimulus level and characteristic frequency is given. For the Population I fibers, with characteristic frequencies below 500 Hz, deviations from the precise interlacing of preferred times of spike discharges in response to rarefaction and condensation clicks, as well as some instances of biased response to condensation clicks are described. The features that set Population II fibers apart from those of Population I are given, and a correlation of these populations with anatomical details of innervation is suggested.

ISSN:0001-4966    

DOI:10.1121/1.1913301

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP