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İşitsel uzaklık algısı çok boyutlu bir olgudur. Ses kaynağına olan aşinalığın, bilişsel ipuçlarından biri olarak mesafe algısında önemli bir etkiye sahip olduğu bilinmektedir. Bu çalışmada, kişiler arası yakınlığın işitsel uzaklık algısı üzerindeki etkilerini değerlendirmek için öznel bir işitsel uzaklık algılama deneyi sunulmaktadır. Öznel deney, 0.5 ve 16 metre arasındaki farklı ses kaynaklarının mesafelerinin simüle edildiği binaural bir dinleme içermekteydi. Katılımcılar 12, farklı cinsiyetten çiftlerdi. Birbirlerini en az bir yıldır tanıyan bu çiftler, kendileri dışındaki diğer çiftlere yabancıydılar. Her bir kişi, eşinden (F0), eşinin sesine en benzeyen yabancıdan (F1) ve eşinin sesine en farklı olan yabancıdan (F2) gelen 5 farklı konuşma kaydını dinleyerek uzaklıklarını değerlendirmiştir. Elde edilen sonuçlara göre, aşinalığın bu üç seviyesi için aşinalığın işitsel uzaklık algısında belirgin bir etkisinin olmadığını gözlenmiştir. Daha detaylı bir çalışmayı gerektiren bir sonuç olarak, kişiler arası ses aşinalığının yanı sıra diğer bilişsel faktörlerin (örneğin, cümlelerin semantik veya fonetik özelliği), işitsel uzaklık algısının geliştirilmesinde en az akustik ipuçları kadar etkili olabileceğini işaret etmiştir. Auditory distance perception is a multidimensional phenomenon. Familiarity with the sound source is known to have an important effect on the distance perception as one of the cognitive cues. An auditory distance perception experiment to assess the effects of interpersonal familiarity on auditory distance perception is reported in this article. The subjective experiment involves a binaural listening experiment where different source distances between 0.5 and 16 meters were simulated. The participants are 12 heterosexual couples who have known each other for at least two years with daily interaction. All couples were strangers to other participated couples. Each subject listened and judged the distance of five different speech utterances from their partner (F0), the spectrally most similar stranger (F1) and the spectrally most dissimilar stranger (F2). The results indicate that there is no significant effect of interpersonal familiarity on auditory distance perception for the three conditions of familiarity. For further investigation, results revealed another interesting point that other cognitive factors besides the interpersonal familiarity (e.g. semantic aspects of the utterances listened) could be as useful as acoustic cues on the enhancement of auditory distance perception. 73

Humans have a strong tendency to spontaneously group visual or auditory stimuli together in larger patterns. One of these perceptual grouping biases is formulated as the iambic/trochaic law, where humans group successive tones alternating in pitch and intensity as trochees (high-low and loud-soft) and alternating in duration as iambs (short-long). The grouping of alternations in pitch and intensity into trochees is a human universal and is also present in one non-human animal species, rats. The perceptual grouping of sounds alternating in duration seems to be affected by native language in humans and has so far not been found among animals. In the current study, we explore to which extent these perceptual biases are present in a songbird, the zebra finch. Zebra finches were trained to discriminate between short strings of pure tones organized as iambs and as trochees. One group received tones that alternated in pitch, a second group heard tones alternating in duration, and for a third group, tones alternated in intensity. Those zebra finches that showed sustained correct discrimination were next tested with longer, ambiguous strings of alternating sounds. The zebra finches in the pitch condition categorized ambiguous strings of alternating tones as trochees, similar to humans. However, most of the zebra finches in the duration and intensity condition did not learn to discriminate between training stimuli organized as iambs and trochees. This study shows that the perceptual bias to group tones alternating in pitch as trochees is not specific to humans and rats, but may be more widespread among animals.

Metrical phonology is the perceptual “strength” in language of some syllables relative to others. The ability to perceive lexical stress is important, as it can help a listener segment speech and distinguish the meaning of words and sentences. Despite this importance, there has been little comparative work on the perception of lexical stress across species. We used a go/no-go operant paradigm to train human participants and budgerigars (Melopsittacus undulatus) to distinguish trochaic (stress-initial) from iambic (stress-final) two-syllable nonsense words. Once participants learned the task, we presented both novel nonsense words, and familiar nonsense words that had certain cues removed (e.g., pitch, duration, loudness, or vowel quality) to determine which cues were most important in stress perception. Members of both species learned the task and were then able to generalize to novel exemplars, showing categorical learning rather than rote memorization. Tests using reduced stimuli showed that humans could identify stress patterns with amplitude and pitch alone, but not with only duration or vowel quality. Budgerigars required more than one cue to be present and had trouble if vowel quality or amplitude were missing as cues. The results suggest that stress patterns in human speech can be decoded by other species. Further comparative stress-perception research with more species could help to determine what species characteristics predict this ability. In addition, tests with a variety of stimuli could help to determine how much this ability depends on general pattern learning processes versus vocalization-specific cues. Electronic supplementary material The online version of this article (doi:10.1007/s10071-016-0968-3) contains supplementary material, which is available to authorized users.

The effect of stimulus intensity (sound pressure level, SPL) of auditory stimuli on the BOLD response in the auditory cortex was investigated in 14 young and healthy subjects, with no hearing abnormalities, using echo-planar, functional magnetic resonance imaging (fMRI) during a verbal and a non-verbal auditory discrimination task. The stimuli were presented block-wise at three different intensities: 95, 85 and 75 dB (SPL). All subjects showed fMRI signal increases in superior temporal gyrus (STG) covering primary and secondary auditory cortex. Most importantly, the spatial extent of the fMRI response in STG increased with increasing stimulus intensity. It is hypothesized that spreading of excitation is associated with the encoding of increasing stimulus intensity levels. In addition, we found bifrontal activation supposedly evoked by the auditory-articulary loop of working memory. The results presented here should assist in the design of optimal activation strategies for studying the auditory cortex with fMRI paradigms and may help in understanding intensity coding of auditory stimuli.