File talk:Voiceless alveolar retracted sibilant.ogg
I doubt that it is an accurate pronunciation. It sounds indistinguishably like an [ʃ] to my ears.
Further corroboration: https://www.reddit.com/r/learnspanish/comments/ga6c77/voiceless_alveolar_retracted_sibilantPeterTrompeter (talk) 11:18, 29 April 2020 (UTC)_s_in/