ToneScope is an audio analysis tool for real-time and offline analysis of sound signals. It uses a multirate FFT approach to achieve high frequency resolution at low frequencies while remaining efficient for real-time use on iOS. Users can analyze audio in real time or record sound locally and analyze it later. All processing is performed entirely on-device. Optional audio recordings are saved locally under user control. No data is transmitted, uploaded, or collected. Designed and developed by Newton Niu.