Phonetics, Speech and Hearing | International Phonetic Association

Anatomy of the vocal tract - from the University of Manitoba
Speech organs - from the University of Oxford. Great graphics; includes downloadable QuickTime movie of x-ray speech)
X-Ray film database for speech research - from Queen's University, Kingston, Canada. Amazing x-ray videos of people talking.
Sound patterns in Human Language: phonation - five still photos of vocal cords in action
A slow-motion animation of the vocal folds vibrating during speech - from UCLA
Epiglottis in motion/pharyngeal stops - from the University of Victoria
Examining the Larynx - from the Voice Center at Eastern Virginia Medical School
Methods of examining larynx - from the University of Stuttgart. Vocal cords in motion

The distinctive vowel sounds of British and American English - from the University of Washington (click to hear the sounds)
Respiration and airstream mechanisms - from the University of Oxford
SIPhTrA voicing basics tutorial - from System for Interactive Phonetics Training and Assessment (SIPhTra) project, UCL.
SIPhTra Plosives 1: basics tutorial
SIPhTra Plosives 2: Voicing onset time and aspiration tutorial
Stress system database - from the University of Oxford. Information on the patterns of primary (word) stress in some 190 languages.
Intro to prosody: chunking, focus, pitch (tutorial) - from Prosody on the Web by the SIPhTrA project
Coarticulation - from SWPhonetics
Sound machines: Vowel Machine, Transcriber, VDIA (practice in recognising vowel sounds), TONI (recognise English nuclear tones) and PLATO (highlight the tonic syllable)

Speech Internet Dictionary - from UCL. Definitions of technical terms used in phonetics, phonology, speech and hearing science and allied disciplines.
Sound waves - from the University of Manitoba
Department of Speech, Music and Hearing at the Royal Institute of Technology, Sweden
Real time spectrogram - from Royal Institute of Technology, Sweden. (online spectrogram includes link to required Snack 16 plug-in)
Spectrogram reading - (in German) from the Institut für Phonetik und Sprachliche Kommunikation, Universität München
The vOICe Sonification Applet - from the Philips Research Laboratories, Eindhoven, The Netherlands
Sound to Graph to Sound with JavOICe - Spectrogram version of preceding site
Airstream Mechanisms and Phonation Types - Ladefoged's clicks, ejectives, etc. in many languages
Airstream mechanisms - from Northwestern University
Types of phonation: creaky, breathy, harsh, falsetto - from the University of Stuttgart
Gas-altered perceived voice pitch:

Helium Voice - from Ask Yahoo (linked to sound file with poor audio quality, but someone may ask about the 'Donald Duck' effect of helium)
Sulfur Hexafluoride Voice - from the University of Maryland

Linguistics 110
Consonant exercises
Vowel exercises
Vowels Consonants - Clickable phonemes in a cross-section of the head - linked to from site #1; requires Shockwave; these two take a while to load, especially the consonants.

Acoustic cues in differentiating phonemes - from UCL. Isolating acoustic cues in phoneme recognition; descriptions, sound files; good companion to chapter 11 of Fry (see (6)).
Simplified Vowel Synthesis Interface - from the University of Delaware. Synthesize non-nasalized monopthongal English vowels using the Klatt synthesizer. Set F0, F1, F2, and duration in ms yourself, and see what you come up with. Links to more complex CV synthesis and general synthesis interfaces.
Zona Land - by Ed Zobel. Excellent interactive tutorials on the physics of waves (with links to other physics topics); I find them to be well-matched companions to D. B. Fry's The Physics of Speech (Cambridge). Example of things you can do at this site: draw two waves yourself then watch how they interfere with each other. VRML plug-in required for some parts. Highly recommended.
The Physics Classroom: Sound Waves and Music - from Glenbrook South High School. A good physics tutorial site with units on waves and decibels; this has dense and very instructive explanatory texts, along with animated graphics.
Standing Waves and Sound - from Concordia College. Samples of some audible frequencies (100 to 5,000 Hz), along with other information on waves.
Understanding decibels - from the Handbook for Acoustic Ecology, Cambridge Street Publishing, 1999. Web version from Simon Fraser University. Technical but clear and potentially useful. With sound files.
Sound Pressure Levels - from CoolMath.com. Decibel level list