By reproducing sounds in 64 tones at a sampling rate of 44.1 kHz, two sound-source ICs bring true acoustics to cellular-phone ring tones. The BU8709KN and BU8899GU sound-source ICs use a PCM sound generator to deliver a multilayered sonic presence. In addition to an equalizer and reverb functions, the chips have other functions that enable users to customize their ring tones. They allow dynamic variation of key and tempo. Included are an ADPCM encoder (one channel) and decoder (two channels). Prices start at $5.50 each in quantities of 1000 with delivery in 8 to 12 weeks.