Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_73540 ( "Horizontal order" real, "Height order" real, "Soundfield type" text, "Number of channels" real, "Channels" text )

### Question ###
If the height order is 1 and the soundfield type is mixed-order, what are all the channels?

### Accurate SQL ###

SELECT "Channels" FROM table_73540 WHERE "Soundfield type" = 'mixed-order' AND "Height order" = '1'