This section shares benchmarking and related research information from inside Starkey Hearing Technologies, including detailed methodology used in data collection.
Open Access Stimuli for
creation of Multi-Talker Maskers
These recordings are open-access files and may be used freely. Please cite the source material in the following manner:
Starkey Hearing Technologies. (2013). Open access stimuli for the creation of multi-talker maskers. Retrieved from: http://www.starkeyevidence.com
The recordings were completed using an AKG Perception 420 condenser microphone. A mesh "pop" filter was positioned approximately four inches in front of the microphone. The microphone signal was fed directly into the preamplifier of a USB interface (M-Audio FastTrack Pro, Avid Technology). Recordings were made in Avid Pro Tools 10 (version 10.3.4) at a sampling rate of 44.1 kHz with 16-bit quantization.
Participants and Recordings
Eight adult male and eight female talkers were recruited for participation. Talkers were all native speakers of English without strong regional accents. Participants stood in an anechoic chamber approximately 6-8 inches from the pop filter. Participants were encouraged to position themselves such that their chin was slightly elevated from a level position. Four separate recordings of the "rainbow passage" (Fairbanks, 1960) were made, for a total of 64 recordings (4 recordings x 8 participants x 2 genders). After the first recording, the talkers were given feedback with regards to their speaking rate and clarity. Subsequent recordings were made without interruption if there was no need for further instruction. Participants were provided with water and were encouraged to take drinks as needed.
Individual recordings were divided into clips at each paragraph of the passage. To assemble the final recordings, the best sample among the four recordings for each talker was identified; these best clips were concatenated to complete the final recording. Segments of silence between paragraphs were cross-faded to reduce audibility of any system noise floor. Twenty-millisecond equal gain fades were applied to the beginnings and ends of each concatenated clip. Clips were exported at their native sampling and quantization parameters.
"Rainbow Passage" Narrative
"When the sunlight strikes raindrops in the air, they act as a prism and form a rainbow. The rainbow is a division of white light into many beautiful colors. These take the shape of a long round arch, with its path high above, and its two ends apparently beyond the horizon. There is, according to legend, a boiling pot of gold at one end. People look, but no one ever finds it. When a man looks for something beyond his reach, his friends say he is looking for the pot of gold at the end of the rainbow. Throughout the centuries people have explained the rainbow in various ways. Some have accepted it as a miracle without physical explanation. To the Hebrews it was a token that there would be no more universal floods. The Greeks used to imagine that it was a sign from the gods to foretell war or heavy rain. The Norsemen considered the rainbow as a bridge over which the gods passed from earth to their home in the sky. Others have tried to explain the phenomenon physically. Aristotle thought that the rainbow was caused by reflection of the sun’s rays by the rain. Since then physicists have found that it is not reflection, but refraction by the raindrops, which causes the rainbows. Many complicated ideas about the rainbow have been formed. The difference in the rainbow depends considerably upon the size of the drops, and the width of the colored band increases as the size of the drops increases. The actual primary rainbow observed is said to be the effect of super-imposition of a number of bows. If the red of the second bow falls upon the green of the first, the result is to give a bow with an abnormally wide yellow band, since red and green light when mixed form yellow. This is a very common type of bow, one showing mainly red and yellow, with little or no green or blue."
- Fairbanks, G. (1960). Voice and articulation drillbook (2nd ed., p. 127). New York, NY: Harper & Row.