This study examined whether speech-on-speech masking is sensitive to variation in the degree of similarity between the target and the masker speech. Three experiments investigated whether speech-in-speech recognition varies across different background speech languages (English vs Dutch) for both English and Dutch targets, as well as across variation in the semantic content of the background speech (meaningful vs semantically anomalous sentences), and across variation in listener status vis-à-vis the target and masker languages (native, non-native, or unfamiliar). The results showed that the more similar the target speech is to the masker speech (e.g., same vs different language, same vs different levels of semantic content), the greater the interference on speech recognition accuracy. Moreover, the listener's knowledge of the target and the background language modulate the size of the release from masking. These factors had an especially strong effect on masking effectiveness in highly unfavorable listening conditions. Overall this research provided evidence that that the degree of target-masker similarity plays a significant role in speech-in-speech recognition. The results also give insight into how listeners assign their resources differently depending on whether they are listening to their first or second language.

The results indicated that a single-microphone NR system based on time-frequency gain manipulation improved the HINT thresholds of listeners. However, to obtain benefit in speech intelligibility, the detectors used in such a strategy were required to detect an unrealistically high percentage of the speech energy and to perform the gain manipulations on a fast temporal basis.

It has been reported that listeners can benefit from a release in masking when the masker speech is spoken in a language that differs from the target speech compared to when the target and masker speech are spoken in the same language [Freyman, R. L. et al. (1999). J. Acoust. Soc. Am. 106, 3578-3588; Van Engen, K., and Bradlow, A. (2007), J. Acoust. Soc. Am. 121, 519-526]. It is unclear whether listeners benefit from this release in masking due to the lack of linguistic interference of the masker speech, from acoustic and phonetic differences between the target and masker languages, or a combination of these differences. In the following series of experiments, listeners' sentence recognition was evaluated using speech and noise maskers that varied in the amount of linguistic content, including native-English, Mandarin-accented English, and Mandarin speech. Results from three experiments indicated that the majority of differences observed between the linguistic maskers could be explained by spectral differences between the masker conditions. However, when the recognition task increased in difficulty, i.e., at a more challenging signal-to-noise ratio, a greater decrease in performance was observed for the maskers with more linguistically relevant information than what could be explained by spectral differences alone.

Multifrequency tympanometry data were measured multiple times between the ages of four weeks and two years from 33 infants/toddlers. Tympanograms were also measured from 33 adult participants. Tympanograms recorded with five probe-tone frequencies (226, 400, 630, 800, and 1000 Hz) were classified using the Vanhuyse et al model classification system (Vanhuyse et al, 1975). Admittance at +200 daPa (Y200) and middle ear admittance (Y(ME)) were calculated. The proportion of Vanhuyse et al patterns in infants and toddlers was different than in adults, especially for younger ages. Y(ME) and Y200 both increased with age. Y(ME) and Y200 data for all infant/toddler groups were significantly lower than adult values at all of the tested probe-tone frequencies. These data can be used as a guide in the clinic to assess normal tympanometric values for infants and toddlers.

Activation of medial olivocochlear efferents through contralateral acoustic stimulation ͑CAS͒ has been shown to modulate distortion product otoacoustic emission ͑DPOAE͒ level in various ways ͑enhancement, reduction, or no change͒. The goal of this study was to investigate the effect of a range of CAS levels on DPOAE fine structure. The 2f 1 -f 2 DPOAE was recorded ͑f 2 / f 1 = 1.22, L 1 = 55 dB, and L 2 =40 dB͒ from eight normal-hearing subjects, using both a frequency-sweep paradigm and a fixed frequency paradigm. Contamination due to the middle ear muscle reflex was avoided by monitoring the magnitude and phase of a probe in the test ear and by monitoring DPOAE stimulus levels throughout testing. Results show modulations in both level and frequency of DPOAE fine structure patterns. Frequency shifts observed at DPOAE level minima could explain reports of enhancement in DPOAE level due to efferent activation. CAS affected the magnitude and phase of the DPOAE component from the characteristic frequency region to a greater extent than the component from the overlap region between the stimulus tones. This differential effect explains the occasional enhancement observed in DPOAE level as well as the frequency shift in fine structure patterns.

Purpose To investigate masking release for speech maskers for linguistically and phonetically close (English and Dutch) and distant (English and Mandarin) language pairs. Method Twenty monolingual speakers of English with normal-audiometric thresholds participated. Data are reported for an English sentence recognition task in English, Dutch and Mandarin competing speech maskers (Experiment I) and noise maskers (Experiment II) that were matched either to the long-term-average-speech spectra or to the temporal modulations of the speech maskers from Experiment I. Results Results indicated that listener performance increased as the target-to-masker linguistic distance increased (English-in-English < English-in-Dutch < English-in-Mandarin). Conclusions Spectral differences between maskers can account for some, but not all, of the variation in performance between maskers; however, temporal differences did not seem to play a significant role.

The Basic English Lexicon materials provide a large set of sentences for native and non-native English speech-recognition testing.

Purpose To examine whether improved speech recognition during linguistically mismatched target–masker experiments is due to linguistic unfamiliarity of the masker speech or linguistic dissimilarity between the target and masker speech. Method Monolingual English speakers (n = 20) and English–Greek simultaneous bilinguals (n = 20) listened to English sentences in the presence of competing English and Greek speech. Data were analyzed using mixed-effects regression models to determine differences in English recogition performance between the 2 groups and 2 masker conditions. Results Results indicated that English sentence recognition for monolinguals and simultaneous English–Greek bilinguals improved when the masker speech changed from competing English to competing Greek speech. Conclusion The improvement in speech recognition that has been observed for linguistically mismatched target–masker experiments cannot be simply explained by the masker language being linguistically unknown or unfamiliar to the listeners. Listeners can improve their speech recognition in linguistically mismatched target–masker experiments even when the listener is able to obtain meaningful linguistic information from the masker speech.