Giant pandas can distinguish their mate through calls

Giant pandas have over a dozen vocal sounds for communication, with a unique 'bleet' used during mating season to signal availability and convey information about size and identity. Researchers studied how well this sound travels through bamboo, finding it most effective within 10 meters.

During which season do giant pandas use the bleet sound more frequently?

What distance is considered optimal for the bleet to be effective in attracting a mate?