Cant hear anything when playing half of the tones

To name two of the tones that I cant hear at all: Cats Purr & Schumanns.

I reinstalled the app twice with no change, would appreciate advice.

iPhone 4, always running the latest OS.

Once all the tones work for me Ill be happy to give full stars as its otherwise a decent app.

SparklingRocks about Mind Wave 2, v1.5