Adding air absorption to simulated room acoustic models.

Room acoustics models are often used in auditory research. The simplest implementations of these models ignore air absorption, and this lack can affect the room response, especially at high frequencies and for large simulated spaces. This letter proposes a method for adding air absorption to a simulated room impulse response calculated without air absorption.

Speech intelligibility in rooms: Disrupting the effect of prior listening exposure.

It has been demonstrated that prior listening exposure to reverberant environments can improve speech understanding in that environment. Previous studies have shown that the buildup of this effect is brief (less than 1 s) and seems largely to be elicited by exposure to the temporal modulation characteristics of the room environment. Situations that might be expected to cause a disruption in this process have yet to be demonstrated.

Speech intelligibility in rooms: Effect of prior listening exposure interacts with room acoustics.

There is now converging evidence that a brief period of prior listening exposure to a reverberant room can influence speech understanding in that environment. Although the effect appears to depend critically on the amplitude modulation characteristic of the speech signal reaching the ear, the extent to which the effect may be influenced by room acoustics has not been thoroughly evaluated. This study seeks to fill this gap in knowledge by testing the effect of prior listening exposure or listening context on speech understanding in five different simulated sound fields, ranging from anechoic space to a room with broadband reverberation time (T60) of approximately 3 s.

Retroactive Streaming Fails to Improve Concurrent Vowel Identification.

The sequential organization of sound over time can interact with the concurrent organization of sounds across frequency. Previous studies using simple acoustic stimuli have suggested that sequential streaming cues can retroactively affect the perceptual organization of sounds that have already occurred. It is unknown whether such effects generalize to the perception of speech sounds.

Time course of a perceptual enhancement effect for noise-masked speech in reverberant environments.

Speech intelligibility has been shown to improve with prior exposure to a reverberant room environment [Brandewie and Zahorik (2010). J. Acoust.

Amplitude modulation detection by human listeners in reverberant sound fields: Carrier bandwidth effects and binaural versus monaural comparison.

Previous work [Zahorik et al., POMA, 12, 050005 (2011)] has reported that for a broadband noise carrier signal in a simulated reverberant sound field, human sensitivity to amplitude modulation (AM) is higher than would be predicted based on the broadband acoustical modulation transfer function (MTF) of the listening environment. Interpretation of this result was complicated by the fact that acoustical MTFs of rooms are often quite different for different carrier frequency regions, and listeners may have selectively responded to advantageous carrier frequency regions where the effective acoustic modulation loss due to the room was less than indicated by a broadband acoustic MTF analysis.

Amplitude modulation detection by human listeners in sound fields.

The temporal modulation transfer function (TMTF) approach allows techniques from linear systems analysis to be used to predict how the auditory system will respond to arbitrary patterns of amplitude modulation (AM). Although this approach forms the basis for a standard method of predicting speech intelligibility based on estimates of the acoustical modulation transfer function (MTF) between source and receiver, human sensitivity to AM as characterized by the TMTF has not been extensively studied under realistic listening conditions, such as in reverberant sound fields. Here, TMTFs (octave bands from 2 - 512 Hz) were obtained in 3 listening conditions simulated using virtual auditory space techniques: diotic, anechoic sound field, reverberant room sound field.

Perceptual Adaptation to Room Acoustics and Effects on Speech Intelligibility in Hearing-Impaired Populations.

Recent evidence suggests that brief listening exposure to a reverberant room environment can improve closed-set speech intelligibility in that same environment. For normal-hearing populations, this room adaptation effect can result in improvements in intelligibility of as much as 20%, but depends strongly on the reverberation time of the room, and appears to require binaural input. Because poor speech intelligibility in reverberation is a common complaint for hearing-impaired listeners, it is important to determine how room adaptation might impact speech intelligibility for hearing-impaired populations.

Adaptation to Room Acoustics Using the Modified Rhyme Test.

The negative effect of reverberant sound energy on speech intelligibility is well documented. Recently, however, prior exposure to room acoustics has been shown to increase intelligibility for a number of listeners in simulated room environments. This room adaptation effect, a possible extension of dynamic echo suppression, has been shown to be specific to reverberant rooms and requires binaural input.

Prior listening in rooms improves speech intelligibility.

Although results from previous studies have demonstrated that the acoustic effects of a single reflection are perceptually suppressed after repeated exposure to a particular configuration of source and reflection, the extent to which this dynamic echo suppression might generalize to speech understanding in room environments with multiple reflections and reverberation is largely unknown. Here speech intelligibility was measured using the coordinate response measure corpus both with and without prior listening exposure to a reverberant room environment, which was simulated using virtual auditory space techniques. Prior room listening exposure was manipulated by presenting either a two-sentence carrier phrase that preceded the target speech, or no carrier phrase within the room environment.

Time-forward speech intelligibility in time-reversed rooms.

The effects of time-reversed room acoustics on word recognition abilities were examined using virtual auditory space techniques, which allowed for temporal manipulation of the room acoustics independent of the speech source signals. Two acoustical conditions were tested: one in which room acoustics were simulated in a realistic time-forward fashion and one in which the room acoustics were reversed in time, causing reverberation and acoustic reflections to precede the direct-path energy. Significant decreases in speech intelligibility--from 89% on average to less than 25%--were observed between the time-forward and time-reversed rooms.