Figure 1: The multichannel lung sound analyzer: SteThoGraph or STG. (a) The arrangement of the microphones in the back pad arrayed over the posterior chest and lateral bases. Twelve microphones are placed on the back; numbers 1 through 6 are on the right side, 9 through 14 are on the left. There is one on each lateral base: microphone numbers 7 and 15, respectively. One microphone is over the trachea: number 16. (b) The placement of the soft foam pad containing the microphones.