Table 4.1 Reference values (reference equivalent threshold sound pressure levels [RETSPLS]) for standard supra- aural audiometric earphones expressed as the sound pressure levels (dB SPL in a 6-cc coupler, type NBS-9A) corresponding to 0 dB hearing level (HL)* Frequency (Hz) 125 250 500 750 1000 1500 2000 3000 4000 6000 8000 TDH-49 and -50 earphones 47.5 26.5 13.5 8.5 7.5 7.5 11.0 9.5 10.5 13.5 13.0 TDH-39 earphones 45.0 25.5 11.5 8.0 7.0 6.5 9.0 10.0 9.5 15.5 13.0 *Adapted from ANSI S3.6-2010. 1. The below figure shows a sine wave. +13 Amplitude 0 -13- 0 1 2 3 4 Time (msec) a. What is the peak amplitude of the above sine wave? b. What is the peak-to-peak amplitude of the above sine wave? LO 5 6 7 c. Calculate the RMS amplitude of the above sine wave. (1 point) (0.5 points) (0.5 points) d. BONUS! What is the frequency of the above wave? You must show your work. (1 point) 2. The below figure shows a sine wave. +3.2 Amplitude 0 -3.2 0 20 120 140 160 40 80 100 Time (microseconds) a. What is the peak amplitude of the above sine wave? b. What is the peak-to-peak amplitude of the above sine wave? c. Calculate the RMS amplitude of the above sine wave. (1 point) (0.5 points) (0.5 points) d. BONUS! What is the frequency of the above wave? You must show your work. (1 point) 3. The below figure shows a sawtooth wave Amplitude +12 "W -12- Time a. What is the peak amplitude of the above sawtooth wave? n b. What is the peak-to-peak amplitude of the above sawtooth wave? c. Calculate the RMS amplitude of the above sawtooth wave. (1 point) (0.5 points) (0.5 points) d. BONUS! The above wave has a frequency of 1700 Hz. What is the cycle period of this wave? You must show your work. (1 point) 4. A sound has an intensity level of 10-3 watts/meter. What is the dB level of this sound? (1 point) 5. Two sounds are measured: Sound "A" has an intensity level of 10-9 watts/meter. Sound "B" has an intensity level of 105 watts/meter. What is the difference in dB between sound "A" and sound "B"? (1 point) 6. You measure the sound pressure of a sound at 2350 Pa. What is the dB level of this sound? (1 pt) 7. The below shows the sound pressure (in uPa) of a sine wave. Recall that dB is calculated based on the RMS value of the sound pressure of the waveform. What is the dB SPL of this waveform? (2 points) +3000 CAA -3000 0 8. Two sounds are measured. Sound "A" has a measured value of 2460 Pa, and sound "B" also has a measured value of 2460 Pa. What is the difference (in dB) between sound "A" and sound "B"? (1 point) 9. During a hearing test, you present a 500 Hz sound at 80 dB HL through TDH-50 earphones. What is the level of sound in dB SPL? (1 point) 10. The siren of an ambulance is 110 dB SPL at 4000 Hz. To match this sound with an audiometer, what level in dB HL would you need to present the sound at through TDH-39 earphones? (1 point) 11. You are listening to music at 73 dB. Your dog barks at 86 dB to get your attention. What is the signal to noise (SNR) ratio for the dog bark (signal) vs the music (noise)? (1 point)