hands, stones hit together, or other things that are useful to create rhythm. There are bone flutes and pipes which are unambiguously paleolithic. Additionally, pierced phalanges (usually interpreted as "phalangeal whistles"), bullroarers, and rasps have also been discovered. The latter musical finds date back as far as the Paleolithic era, although there is some ambiguity over archaeological finds which can be variously interpreted as either musical or non-musical instruments/tools. Another possible origin of music is motherese, the vocal-gestural communication between mothers and infants. This form of communication involves melodic, rhythmic and movement patterns as well as the communication of intention and meaning, and in this sense is similar to music. Geoffrey Miller suggests musical displays play a role in "demonstrating fitness to mate." Based on the ideas of honest signal and the handicap principle, Miller suggested that music and dancing, as energetically costly activities, demonstrated the physical and psychological prowess of the singing and dancing individual. Similarly, communal singing occurs among both sexes in cooperatively breeding songbirds of Australia and Africa, such as magpies and white-browed sparrow-weavers. Archaeoacoustic methodology The field of archaeoacoustics uses acoustic techniques to explore prehistoric sounds, soundscapes, and instruments; it has included the study of ringing rocks and lithophones, of the acoustics of ritual sites such as chamber tombs and stone circles, and the exploration of prehistoric instruments using acoustic testing. Such work has included acoustic field tests to capture and analyze the impulse response of archaeological sites; acoustic tests of lithophones or 'rock gongs'; and reconstructions of soundscapes as experimental archaeology. Africa Egypt In prehistoric Egypt, music and chanting were commonly used in magic and rituals. The ancient Egyptians credited the goddess Bat with the invention of music. The cult of Bat was eventually syncretised into that of Hathor because both were depicted as cows. Hathor's music was believed to have been used by Osiris as part of his effort to civilise the world. The lion-goddess Bastet was also considered a goddess of music. Rhythms during this time were unvaried and music served to create rhythm. Small shells were used as whistles. During the predynastic period of Egyptian history, funerary chants continued to play an important role in Egyptian religion and were accompanied by clappers or a flute. Despite the lack of physical evidence in some cases, Egyptologists theorise that the development of certain instruments known of the Old Kingdom period, such as the end-blown