This article, published by Lord Rayleigh in 1907, explores the human ability to perceive sound direction. Rayleigh conducted extensive experiments to understand how the human ear distinguishes the direction of sounds, particularly focusing on the discrimination between right and left directions. He found that pure tones could not be localized to the right or left, but with other sounds, such as the human voice, this discrimination was possible. The discrimination between front and back was more challenging, especially with low-pitched sounds. Rayleigh's experiments involved using tuning forks and resonators to produce pure tones and observing the perceived direction of the sound. He discovered that the discrimination between right and left was primarily based on phase differences rather than intensity differences, especially for low-pitched sounds. For higher pitches, the discrimination was more complex and less reliable due to the increased phase differences. The article also discusses the practical implications of these findings, such as the importance of being able to estimate the bearing of fog signals at sea. Rayleigh suggests that combining judgments from multiple observers can improve the accuracy of direction estimation. Overall, the study provides insights into the physiological mechanisms of sound localization and has implications for various applications, including auditory perception and signal processing.This article, published by Lord Rayleigh in 1907, explores the human ability to perceive sound direction. Rayleigh conducted extensive experiments to understand how the human ear distinguishes the direction of sounds, particularly focusing on the discrimination between right and left directions. He found that pure tones could not be localized to the right or left, but with other sounds, such as the human voice, this discrimination was possible. The discrimination between front and back was more challenging, especially with low-pitched sounds. Rayleigh's experiments involved using tuning forks and resonators to produce pure tones and observing the perceived direction of the sound. He discovered that the discrimination between right and left was primarily based on phase differences rather than intensity differences, especially for low-pitched sounds. For higher pitches, the discrimination was more complex and less reliable due to the increased phase differences. The article also discusses the practical implications of these findings, such as the importance of being able to estimate the bearing of fog signals at sea. Rayleigh suggests that combining judgments from multiple observers can improve the accuracy of direction estimation. Overall, the study provides insights into the physiological mechanisms of sound localization and has implications for various applications, including auditory perception and signal processing.