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2. What is Sound? Sound RecordingsSound WavesDigital MusicPitchAnalog to DigitalThe Doppler Effect ConverterIntensityFactors Affecting theDecibel ScaleQuality of a Digital RecordingLoudness Digital Audio Editing 2 of 29 3. Sounds are nothing more than waves of airpressure. We are able to hear sounds becauseour ears are sensitive to these waves ofpressure3 of 29 4. A sound wave can be represented as awaveform which graphically describes theshape of the wave.4 of 29 5. Click on each animation to learn about these two typesNon-PeriodicPeriodic5 of 29 6. Page 1 of 2Sound that is created by a short, sudden event like a hand clap.The air that was between your hands is pushed aside increasingthe air pressure in the space near your hands. This increase inpressure occurs because more air molecules are temporarilycompressed into less space. The increased pressure pushes theair molecules outwards in all directions. When the pressurereaches your ear, it pushes on your eardrum causing you tohear the clap 6 of 29 7. # 8. Page 1 of 2Sound created by a vibrationA good example of a periodic wave occurs when you ring a bell.After the initial strike (which is like a hand clap), the soundcomes from the vibration of the bell.When the bell is ringing, it vibrates at a particular frequency(depending on the size and shape of the bell) causing nearbyair to vibrate with the same frequency.8 of 29 9. Page 2 of 2 Waveform for a typical bell vibrationWaves of air pressure travel outwards from the bell.Pressure waves from continuous vibration resemble the illustration. 9 of 29 10. Listen to the sound by clicking on the icon below the images, then click on the answers button ANSWERS 10 of 29 11. Wavelength describes the horizontal length ofone cycle of a wave or the distance from onepeak or trough to the next, as shown.Amplitude =height of thewave The higher the amplitude, the louder the sound11 of 29 12. Sometimes referred to as frequency.Describes the number of waves that pass apoint in one secondCharacteristic of sound that makes it soundhigh or low.12 of 29 13. 13 of 29 14. Pitch is measured in Hertz (Hz).The lower the pitch, the deeper the sound. 14 of 29 15. The audible range offrequencies (pitch)is usually between 20 Hz to20,000 Hz.There is considerablevariation between individuals,especially at the highfrequency end.15 of 29 16. As a sound approaches, thepitch gets higher.As a sound moves away, thepitch gets lower. 16 of 29 17. Also known as sound pressure level (SPL).Measured in decibels (dB). 0 dB = being completely quiet 20 dB = whispering 60 dB = normal conversation 100 dB = mp3 player at its loudest 110 dB = front row at a rock concert 160 dB = instance perforation of eardrum 17 of 29 18. 18 of 29 19. The same sound will not be perceived to have thesame loudness to all individuals. 20 dB = whispering Elderly people might not hear you 60 dB = normal conversation Elderly people still might not hear you 80dB = yelling at your grandpa! He might finally hear what youre saying! 19 of 29 20. The same loudness measured in dB doesntsound the same for everybody.20 of 29 21. The first recorded sounds 1860 and 1877Click to read more 21 of 29 22. The first way that sound was able to be recorded.22 of 29 23. Analog recordings are the opposite of digitalrecordings.Modern examples of analog recordings are:Vinyl recordsReel-to-reel tapes Cassette tapes 23 of 29 24. To digitally record sound means that you recordit using a computer.The analog signal of a sound (sound waves) isconverted into a stream of discrete numbers thatrepresent the changes in air pressure over time.24 of 29 25. Recording digitally has many benefits over analogrecording. You can copy digital files as many times as youlike without any loss of quality You can burn digital files to a CD You can share digital files on the Internet You can edit the digital files more easily 25 of 29 26. Music downloaded from iTunes and other places Listening to Podcasts Recording something using a microphone andyour computer Audio Books26 of 29 27. The device used in digitalrecording.The ADC captures a snapshotof the electric voltage on anaudio line.The snapshot is thenCLICK TO ENLARGErepresented as a digital numberthat can be sent to a computer. 27 of 29 28. Sample rateSample size The rate at which The number of digitssamples are captured in the digitalor played back representation of Measured in Hertz, oreach samplesamples per second An audio CD has asample rate of 44,100Hz (44 KHz)I STILL DONT UNDERSTAND!28 of 29 29. We will be using Audacity to work with audio.To download Audacity, click on the icon, aboveYou are now ready to move on to the nextsection, Working with Digital Audio 29 of 29 30. Extra Slide #1 31. Extra Slide #2