This is awesome, I love the simplicity of it as well. Agree with others that more sounds would be great as well. Give some basics away as a free tier and make a higher tier that includes more sounds.
For my personal hobbies I wouldn't want to pay, but I could definitely see using this for my team. Dashing is prevalent throughout my company (we have them on TV's throughout the office), so if you monetize toward that angle, perhaps as an already baked widget that would definitely be appealing as well.
Yeah been thinking about a paid tier with more customisability. Do you think it's something you would pay (a small monthly amount) for?