I. Using the reference pressure of .0002dynes/cm' Example: You have a measured pressure of 20,000 uPa or .02 Pa dBSPL = 20 log (PO/PR) dBSPL = 20 log (20,000 uPa/20uPa or (.02 Pa/.00002 Pa) dBSPL = 20 log (1000) dBSPL = 20 X 3 dBSPL = 60 What is the dBSPL for each of the following outputs? a. .002 Pa b. 200 Pa c. 2 Pa d. .0002 Pa II. Using the reference power output of 10-" watts/m' Example: You have a measured pressure of 10watts/m' dBIL = 10log ( Divided dBIL = 10log (10'watts/m'/10"watts/m') dBIL = 10log (10'-10") dBIL = 10log (10") dBIL = 10 X 13 dBIL = 130 What is the dBIL for each of the following? a. 1000 watts/m' (make sure you put this into a base 10 logarithm) b. 100 watts/m III. Find the frequency for the following: Helpful hints: Frequency = 1/period; Wavelength (2) = speed of sound/frequency Speed of sound = 331m/sec at normal atmospheric pressure; Period = the amount of time needed to complete one cycle; T = time; Period = 1/frequency a. T = .02 b. T=.00005 c. 2 =.05 d. 2 = 1.3 IV. Given OdBHL for 1000 Hz is 7dBSPL and OdBHL for 2000 Hz is 9dBSPL Helpful hint: SPL readings are physical sound measures, HLis the measurement found on the audiometer dials for hearing testing. SPL changes as a function of frequency so audiometric equipment is calibrated so that 0 on the dial equals the correct amount of SPL. This makes it easier to plot on an audiogram. Also, the term SL refers to the number of dB above or below a threshold, so if someone's threshold is 10dBHL and you want to test at 30dBSL, the tone would be presented at 40dBHL (10dB + 30dB). Example: At 1000Hz, the SPL for a 30dBHL signal is equal to 37dBSPL (add to convert HL to SPL subtract for the opposite). Calculate the following: a. What is the SPL in dB for 45dBHL at 1000 Hz? b. What is the SPL in dB for 38dBHL at 2000 Hz? c. What is the HL in dB for 42dBSPL at 1000 Hz? d. Given a person's threshold at 1000 Hz is 20dBHL; what is the HL in dB when the tone is presented at 15dBSL