As the audio stream initiates, the mesmerizing sound of the "Volca Keys Preset 4" greets the listener. The distinctive feature of this audio piece is the rich, immersive tones produced by a Volca synthesizer, showcasing its preset functionalities. It's an analog sound, a classic feature of the Volca series, giving it a warm, nostalgic feel. The synth's fluctuating tones resonate deeply, creating a captivating soundscape that's both soothing and stimulating. The audio progresses, altering between different pitch levels, showcasing the versatility and range of the preset. The harmony of the analog synth is on full display, weaving a tapestry of sound that's both complex and compelling. The synthesis of tones creates a vibrant auditory experience, emblematic of the Volca Keys Preset 4, making it a true testament to the power and potential of analog synthesizers.