Statistics of Natural Binaural Sounds - Supplementary Material

Wiktor Mlynarski, Juergen Jost (2014) 

Statistics of Natural Binaural Sounds,

PLOS One 9(10): e108968. doi:10.1371/journal.pone.0108968

 

Each file is a 12 minute binaural recording of a natural auditory scene. Data were used to analyze statistics of stimuli processed by the auditory system in the natural environment. 

 

1. Nocturnal nature - the recording subject sat in a randomly selected position in the garden during summer evening. During the recording the subject was keeping his head still, looking ahead, with his chin parallel to the ground. The dominating background sound were grasshopper calls. Other acoustic events included sounds of a distant storm and a few cars passing by on a near-by road. The spatial configuration of this scene did not change much in time - the scene was almost static.

 

2. Forest walk - this recording was performed by a subject freely moving in the wooded area. The second speaker was present, engaged in a free conversation with the recording subject. In addition to speech, this scene included environmental sounds such as flowing water, cracks of broken sticks,leave crunching, wind etc. Binaural signal was affected not only by the spatial scene configuration, but also by head and body motion patterns of the recording subject.

 

3. City center - the recording subject sat in a touristic area of an old part of town, fixating the head as in the previous case. During the recording many moving and static human speakers were present. Contrasted with the previous example, the spatial configuration of the scene varied continuously.

 

Two of the analyzed auditory scenes (nocturnal nature and city center) were recorded by a non-
moving subject, therefore sound statistics were unaffected by listener’s motion patterns and self generated sounds. In the third scene (forest walk) the subject was moving freely and was speaking sparsely. 

Recordings were performed using the Soundman OKM-II binaural microphones which were placed in the left and the right ear channels of the recording subject. Soudmann DR2 recorder was used to simultaneously record sound in both channels in an uncompressed wave format at 44100 Hz sampling rate. The head circumference of the recording subject was equal to 60 cm.