$(14$ Points$)$ A hotel started playing joyful, happy music at the reception desk during customer checkouts. Subsequently, the hotel observed an improvement in the ratings and reviews provided by customers on satisfaction forms completed at checkout.

a$.$ Explain this change in customers' attitudes in terms of affective foundations of attitudes.

b$.$ Describe how "differential memory accessibility account", which is based on the associative network model, could explain the changes in customer satisfaction ratings in this scenario.