Feedback Trainer vs Redlined

A frequency ear training app for PA engineers and audio professionals. The ability to quickly identify problem frequencies that cause feedback is a skill built through experience. Train your ears with this app and sharpen your instincts for the stage and studio. Features Visual learning with a 31-band graphic EQ display Two modes: Phone-Friendly (100Hz–16kHz) and Full Range for external speakers (40Hz–16kHz) Hint mode for beginners Track your accuracy and progress history Available in Japanese, English, Chinese, French, and Spanish

Redlined is an iPhone audio recorder for DJ sets. Record from the built-in microphone or a supported connected audio input. Choose AAC, 24-bit WAV, or 32-bit float WAV. Watch live input levels and keep an active recording going in the background, with a Live Activity showing its status and elapsed time. Your local library keeps your recordings together. Add titles, dates, notes, and cover artwork; play, duplicate, export, or trim supported files into a separate copy. Import audio from Files and work with a local copy. Free recording supports any number of sets up to 30 minutes each. Redlined Unlimited is a one-time purchase that removes the per-recording time limit. All saved recordings remain available without a purchase. Compatibility depends on your iPhone and recording interface. Make a short test recording and listen back to confirm your setup. Storage, device, and file-format limits still apply.