High-frequency sounds cut off by cell phones might carry more information than previously thought.

The human voice routinely produces sounds at frequencies above 5000 Hz, but it has long been assumed that this treble range, which includes high sounds such as cricket chirps, is superfluous to the understanding of human speech. Now researchers from the University of Arizona, in Tucson, are taking a second look at this underappreciated range.

Their research reveals that people can glean a large amount of information, including the identification of familiar songs or phrases, from just the higher frequencies. The work may prompt a re-evaluation of how much spectrum is necessary to carry the full meaning of the spoken word.

Although current cell phone technology only transmits frequencies between 300 and 3400 Hz, musicians have known for decades that an unbalanced or cut-off treble range can ruin the quality of vocals at concerts.

The researchers recorded male and female voices singing and speaking the words to the national anthem and then removed all the frequencies below 5700 Hz. When volunteers listened to the high-frequency recordings, they were able to identify the gender of the voice, the familiar passages from the Star-Spangled Banner, and whether the voice was singing or speaking the words.

The study was conducted by Brian Monson, PhD, A. Davi Vitela, Brad Story, PhD, and Andrew Lotto, PhD, of the Department of Speech, Language and Hearing Sciences at the University of Arizona.

They presented their findings recently at the 162nd meeting of the Acoustical Society of America in San Diego.