Wolfram’s sites offer a lot of resources about mathematics.

From wolfram.com:

Founded by Stephen Wolfram in 1987, Wolfram Research is one of the world’s most respected software companies—as well as a powerhouse of scientific and technical innovation. As pioneers in computational science and the computational paradigm, we have pursued a long-term vision to develop the science, technology, and tools to make computation an ever-more-potent force in today’s and tomorrow’s world.

Their software Mathematica, not for free, allows to compute data to create interactive demonstrations; look at some examples here.

There is the possibility to examine for free a lot of  their applications downloading and installing their player, unfortunately for Windows only, after that it is enough you visit the demonstrations page, browse a topic – e.g. Physical Sciences …

… and choose a subtopic, e.g. Physics and then Acoustics …

Now you can try about some demonstrations; here some examples from wolframmathematica youtube channel:

and others from the subtopic  Physical Sciences/Physics/Waves:

Obviously you can try a lot of interactive demonstrations by tags, … sounds, audio, harmonics, … so:

• download and install the player
• choose an interactive demonstration
• enjoy

Again, at wolframalpha.com/widgets you can try or create  widgets  for your site/blog.