Table 1 Measured levels (dBA) and free-field predictions for acoustical survey sound sources, with source-receiver distances (meters)
Peak sound level measures for typical background noise level: ≈35 dBA; windy gusts: 50–70 dBA | PUTUTU Strombus conch shell horn (Lobatus galeatus) | WHISTLE metal/cork safety (proxy for Andean flute/whistle) | CLAPPER wooden percussion | VOICE male; Quechua & Spanish speech (tenor/baritone range) | ESS (2^19) repeated exponential sine sweep via mini loudspeaker | |||||
|---|---|---|---|---|---|---|---|---|---|---|
MEAS. (dBA) | Free-field (FF) prediction | MEAS. (dBA) | FF pred. | MEAS. (dBA) | FF pred. | MEAS. (dBA) | FF pred. | MEAS. (dBA) | FF pred. | |
Characteristic frequencies | 300 Hz tone; harmonic peaks ≈610 Hz & ≈920 Hz | 3 kHz dominant tonal area (≈2.6−3.2 kHz) | broadband; esp > 1 kHz | Varies w/words; low-mid frequencies emphasized (≈150 Hz; ≈350–450 Hz; ≈500–600 Hz; ≈1.25 kHz articulation peak) | 150 Hz–20 kHz (broadband) but low frequencies less robust due to loudspeaker | |||||
1 m calibration | 96 dBA | – | 105 dBA | – | 95 dBA | – | 75 dBA | – | 90 dBA | – |
Source (S1) at top-CENTER | ||||||||||
S1-R1 (7 m) | 82 | 80 | 89 | 89 | 80 | 79 | 70 (audio) | 59 | 76 | 74 |
S1-R2 (14 m) | 77 | 74 | 79 | 83 | 80 | 73 | 64 (audio) | 53 | 71 | 68 |
S1-R3 (25 m) | 78 | 68 | 79 | 77 | 81 | 67 | 59 (audio) | 47 | 62 | 62 |
S1-R4 (27 m) | 61 | 68 | 66 | 77 | 57 | 67 | 58 (audio) whispers understood | 47 | 52 | 62 |
S1-R5 (37 m) | 58 | 65 | 60 | 74 | 57 | 64 | 45 | 44 | 53 | 59 |
S1-R6 (64 m) | 54 | 60 | 50 | 69 | 44 | 59 | 51 | 39 | 43 | 54 |
Source (S2) at E-wall niche overlooking plaza | ||||||||||
S2-R6 (43 m) | 67 | 64 | 70 | 73 | 66 | 63 | 62 clearly understood | 43 | 57 | 58 |
S2-R7 (133 m) | 51 | 54 | 60 | 63 | 45 | 53 | 39 | 33 | 43 | 48 |
S2-R8 (225 m) | 40 | 49 | 45 | 58 | 21 (audio) | 48 | 34 (audio) | 28 | 40 | 43 |