The Physics of Sound
Physicians have determined that sound waves function a lot like waves in the ocean. Different types of sound produce waves that have a unique frequency, intensity, and speed. The physics of sound includes the study and understanding of how these waves behave and how they interact with the surrounding particles of the air, water, or solid object they travel through.
A related topic, acoustics, is the study of sound or the science of sound. Acoustics may include the anatomy, physiology, psychology, and physics of sound, and while this site will cover each of these concepts to a certain extent we will focus primarily on the physics of sound. Musicians, physicians, and acoustical scientists should find this list of resources useful for learning or relearning the basic concepts of sound physics as well as sound intensity, tuning, scales, and temperament and hearing.
Basic Concepts
- Occupational Safety & Health Administration: The Physics of Sound: This government page was written to inform state employees and advocates about sound safety. It includes a 'Basic Qualities' section as well as more technical sections on sound attributes. Use the links at the top of the page to jump down to the section you are looking for.
- The Method Behind The Music: Traveling Waves: Musicians interested in learning more about sound should visit this musically focused website. It explains the sound waves and their interactions in simple English.
- Georgia State University: HyperPhysics Concepts: Georgia State created this extensive interactive flowchart on all things sound. It covers sound waves, music, hearing, and basically anything else you can think of. Click on the topic you would like to learn more about, and you will find related subtopics, graphs, or glossary definitions.
- University of California Santa Cruz: Sound Propagation: This technical essay from the UC Santa Cruz offers an introduction to how sound moves. It covers graphs, equations and technical jargon, but the article is kept clear and easy to understand.
- Nondestructive Testing Resource Center: Sound: Although this is meant as a resource for high school students, more advanced students can still find plenty of useful information on sound and hearing. Use this table of contents to find what you are looking for.
- Illuminations: Sound Wave: After learning about the basics of sound you may want to look at this sound wave simulation. You can intuitively interact with sound particles in way that is highly intriguing.
Intensity
- How Stuff Works: What is a decibel, and how is it measured?: This article provides a clear introductory lesson on the decibel system and how we measure the intensity of sound. And with any How Stuff Works article, you can follow embedded links or find related articles on related topics.
- The Physics Classroom: Intensity and the Decibel Scale: This site offers a thorough explanation of the intensity of sound and how frequency relates to decibels. It also offers a table that compares the intensity of different noises from rustling leaves to a military jet takeoff.
- The Engineering Toolbox: Sound Intensity: If you are looking for a mathematical perspective, this page offers factors and equations the are used to determine decibels. It also provides equations for sound distance and sound pressure.
- Discovery of Sound in the Sea: Introduction to Decibels: Although this website is about sound in the ocean, it provides surprisingly helpful information about decibels and sound intensity (especially if you understand a bit of math). You can also find plenty of additional information on sound if you visit the Science of Sound page.
- The Physics Lab: Sound Level Intensity: Physicians or mathematicians may find this website useful for understanding the science behind sound intensity. It offers physics equations and force diagrams, among other physics resources.
Tuning, Scales and Temperament
- University of Wisconsin: Relating Tuning and Timbre: The music department at the University of Wisconsin explains that this page contains an article that was taken from the Experimental Musical Instruments publication. The article talks about tuning and timbre as well as scales, consonance, and other complex musical theories.
- Yuval Nov: Explaining the Equal Temperament: At first glance this page may seem like a historical account of musical temperament, but it actually offers incredibly detailed explanations of notes, intervals, melody, and octaves. You can also find introductory information on temperament and a description of equal temperament.
- Pierre Lewis: Understanding Temperaments: If you are seriously interested in learning about temperament, this is a good site to visit after you have received an introductory lesson. Here, you will find detailed information, graphs and equations on the different forms of temperament. You can also find endless amounts of additional information if you follow the links embedded in the article.
- Michigan Technological University: Scales – Just vs Equal Temperament: This page was designed to help music students understand and utilize the mechanics behind scales. It offers non-technical information as well as tables on the frequency and temperament of musical intervals and notes.
- Harmonics: 2394 Unique Musical Scales: Music enthusiasts should visit this site to find a seemingly endless list of musical scales along with notes on tuning and temperament. At the beginning of the page you can also find a few links that the author provides on related topics.
Hearing
- American Speech-Language-Hearing Association: How We Hear: This brief page offers enough introductory information on hearing to understand how the ear functions and what role each section of the ear plays in the hearing process. You can follow the “outer ear," “middle ear,” and “inner ear” links on the page to read more on those topics.
- National Institutes of Health: How Your Brain Understands what Your Ears Hear: This student resource page offers simple and visually appealing lessons on how we hear and interpret sound. Lessons 3 and 4 are especially helpful, but be sure to watch all parts of the lesson. You will need Macromedia Flash Player to run these applets. If you do not have it, you can find a link at the bottom of each lesson page.
- Dangerous Decibels: How we Hear: On this brief page you will find a labeled diagram of the inner, middle, and outer ear. There is also an easy-to-understand introduction of how our ear interprets and processes sound. If you are interested in learning about hearing loss, use the links on the right hand “Information Center” menu.
- Think Quest: How We Perceive Sound: Think Quest runs this website, The Soundry, which is an educational resource for students who study acoustics. The page shows diagrams of the different sections of the ear and how they function to help us hear. You can also find addition information on sound by visiting the Soundry front page.
- The University New South Wales: Voice Acoustics: The school of physics at UNSW has provided this page on how we hear and make vocal sounds. It provides detailed information on the anatomy, psychology, and physics behind voice acoustics. Use the table of contents links at the top of the page to skip down to the section that interests you.
- American Academy of Otolaryngology: Noise and Hearing Protection: This site not only covers hearing loss protection, but it also goes into how we hear and how decibels work. If you find learning about hearing from a health perspective useful, you can read more about hearing and sound on this website by following the “Related Pages” links at the bottom of the page.