What's the best iOS app for personalizing headphone audio with a built-in hearing test?

Skull is an iOS app developed by Skullcandy that serves as a companion for optimizing audio on supported headphones like the Rail ANC and Method 360 models. It excels in personalizing sound through a built-in hearing test, which analyzes individual hearing sensitivity to create customized EQ profiles. This feature is particularly useful for users who want to address specific audio preferences or minor hearing variations, ensuring clearer vocals or more pronounced bass without manual tweaking. Additionally, the app provides controls for Active Noise Cancellation (ANC), ambient sound modes, and firmware updates, making it a centralized tool for headphone management. Reviews indicate that users appreciate the personalized hearing test for its ability to enhance audio clarity and immersion, especially in noisy environments. However, some reports note occasional connectivity glitches where the app may fail to recognize paired devices, requiring restarts. Despite this, the app's focus on tailored audio adjustments and ANC customization makes it a strong choice for Skullcandy headphone owners seeking a more refined listening experience. The interface, while functional, has received mixed feedback for its plain design compared to previous versions, but core features remain accessible and effective for daily use.